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Mia Steinkirch 2019-10-27 20:26:35 -07:00
parent 3c5ee16ff0
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18
ebook_src/USEFUL/advanced/lru_cache.py
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#!/usr/bin/env python3
__author__ = "bt3"
from functools import lru_cache
@lru_cache(maxsize=20)
def fib(n):
if n < 2:
return n
return fib(n-1) + fib(n-2)
if __name__ == '__main__':
print([fib(n) for n in range(10)])
print(fib.cache_info())

31
ebook_src/USEFUL/basic_examples/example_OrderedDict.py
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#!/usr/bin/env python
__author__ = "bt3"
from collections import OrderedDict
def OrderedDict_example():
''' show some examples for OrderedDict '''
''' keep the order of insertion.
maintains a doubly linked list, so size is more than twice than normal dict'''
pairs = [('a', 1), ('b',2), ('c',3)]
d1 = {}
for key, value in pairs:
if key not in d1:
d1[key] = []
d1[key].append(value)
for key in d1:
print(key, d1[key])
d2 = OrderedDict(pairs)
for key in d2:
print(key, d2[key])
if __name__ == '__main__':
OrderedDict_example()

17
ebook_src/USEFUL/basic_examples/example_args.py
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#!/usr/bin/env python
__author__ = "bt3"
def simple2(a, *args):
print args
def simple(*args):
print args
def simple3(**kwargs):
print kwargs
simple(1, 2, 3)
simple2(1, 2, 3)
simple3(x=1, y=2)

28
ebook_src/USEFUL/basic_examples/example_benchmark_decorator.py
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#!/usr/bin/env python
__author__ = "bt3"
import random
def benchmark(func):
import time
def wrapper(*args, **kwargs):
t = time.clock()
res = func(*args, **kwargs)
print("\t%s" % func.__name__, time.clock()-t)
return res
return wrapper
@benchmark
def random_tree(n):
temp = [n for n in range(n)]
for i in range(n+1):
temp[random.choice(temp)] = random.choice(temp)
return temp
if __name__ == '__main__':
random_tree(10000)

37
ebook_src/USEFUL/basic_examples/example_comp_lists.py
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#!/usr/bin/env python
__author__ = "bt3"
a = [3, 4, 5, 6, 7]
# Filter elements greater than 4
# Bad:
b = []
for i in a:
if i > 4:
b.append(i)
print b
# Good:
print [i for i in a if i > 4]
# Or:
print filter(lambda x: x > 4, a)
# Add three to all list members:
# Bad
b = []
for i in range(len(a)):
b.append(a[i] + 3)
print b
# Good:
print [i + 3 for i in a]
# Or:
print map(lambda i: i + 3, a)

32
ebook_src/USEFUL/basic_examples/example_counter.py
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#!/usr/bin/env python
__author__ = "bt3"
from collections import Counter
def Counter_example():
''' it is a dictionary that maps the items to the number of occurrences '''
seq1 = [1, 2, 3, 5, 1, 2, 5, 5, 2, 5, 1, 4]
seq_counts = Counter(seq1)
print(seq_counts)
''' we can increment manually or use the update() method '''
seq2 = [1, 2, 3]
seq_counts.update(seq2)
print(seq_counts)
seq3 = [1, 4, 3]
for key in seq3:
seq_counts[key] += 1
print(seq_counts)
''' also, we can use set operations such as a-b or a+b '''
seq_counts_2 = Counter(seq3)
print(seq_counts_2)
print(seq_counts + seq_counts_2)
print(seq_counts - seq_counts_2)
if __name__ == '__main__':
Counter_example()

42
ebook_src/USEFUL/basic_examples/example_decorators.py
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#!/usr/bin/env python
__author__ = "bt3"
def logger(func):
def inner(*args): #1
print "Arguments were: {0}".format(args)
return func(*args)
return inner
@logger
def foo(x, y):
return x+y
print foo(1, 2)
def sum(func):
s = 0
for i in func():
s += i
return s
@sum
def interate():
a = []
for i in range(10):
a.append(i)
return a
print interate
# which is the same as
def interate():
a = []
for i in range(10):
a.append(i)
return a
print sum(interate)

27
ebook_src/USEFUL/basic_examples/example_defaultdict.py
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#!/usr/bin/env python
__author__ = "bt3"
from collections import defaultdict
def defaultdict_example():
''' show some examples for defaultdicts '''
pairs = {('a', 1), ('b',2), ('c',3)}
d1 = {}
for key, value in pairs:
if key not in d1:
d1[key] = []
d1[key].append(value)
print(d1)
d2 = defaultdict(list)
for key, value in pairs:
d2[key].append(value)
print(d2)
if __name__ == '__main__':
defaultdict_example()

15
ebook_src/USEFUL/basic_examples/example_doctest.py
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#!/usr/bin/python
__author__ = "bt3"
'''
The doctest module automatically runs any statement beginning with >>>
and compares the following line with the output from the interpreter.
>>> 1 == 1
False
'''
if __name__ == '__main__':
import doctest
doctest.testmod()

45
ebook_src/USEFUL/basic_examples/example_fractions.py
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#!/usr/bin/env python
__author__ = "bt3"
from fractions import Fraction
def rounding_floats(number1, places):
return round(number1, places)
def float_to_fractions(number):
return Fraction(*number.as_integer_ratio())
def get_denominator(number1, number2):
a = Fraction(number1, number2)
return a.denominator
def get_numerator(number1, number2):
a = Fraction(number1, number2)
return a.numerator
def test_testing_floats(module_name='this module'):
number1 = 1.25
number2 = 1
number3 = -1
number4 = 5/4
number6 = 6
assert(rounding_floats(number1, number2) == 1.2)
assert(rounding_floats(number1*10, number3) == 10)
assert(float_to_fractions(number1) == number4)
assert(get_denominator(number2, number6) == number6)
assert(get_numerator(number2, number6) == number2)
s = 'Tests in {name} have {con}!'
print(s.format(name=module_name, con='passed'))
if __name__ == '__main__':
test_testing_floats()

27
ebook_src/USEFUL/basic_examples/example_generator.py
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#!/usr/bin/env python
__author__ = "bt3"
def interate(x):
for i in range(x):
yield i
def gen1():
a = interate(10)
print a.next()
print a.next()
print a.next()
def reverse(data):
for i in range(len(data)-1, -1, -1):
yield data[i]
def gen2():
for c in reverse('awesome'):
print c
if __name__ == '__main__':
gen1()
gen2()

7
ebook_src/USEFUL/basic_examples/example_lambda.py
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#!/usr/bin/env python
__author__ = "bt3"
test = lambda x: x**2
print test(3)

21
ebook_src/USEFUL/basic_examples/example_logging.py
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#!/usr/bin/env python
__author__ = "bt3"
import logging
LOG_FILENAME = 'logging_example.out'
logging.basicConfig(filename=LOG_FILENAME,
level=logging.DEBUG,
)
logging.debug('This message should go to the log file')
f = open(LOG_FILENAME, 'rt')
try:
body = f.read()
finally:
f.close()
print 'FILE:'
print body

60
ebook_src/USEFUL/basic_examples/example_numpy.py
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#!/usr/bin/env python
__author__ = "bt3"
import time
import numpy as np
def testing_numpy():
''' tests many features of numpy '''
ax = np.array([1,2,3])
ay = np.array([3,4,5])
print(ax)
print(ax*2)
print(ax+10)
print(np.sqrt(ax))
print(np.cos(ax))
print(ax-ay)
print(np.where(ax<2, ax, 10))
m = np.matrix([ax, ay, ax])
print(m)
print(m.T)
grid1 = np.zeros(shape=(10,10), dtype=float)
grid2 = np.ones(shape=(10,10), dtype=float)
print(grid1)
print(grid2)
print(grid1[1]+10)
print(grid2[:,2]*2)
def trad_version():
t1 = time.time()
X = range(10000000)
Y = range(10000000)
Z = []
for i in range(len(X)):
Z.append(X[i] + Y[i])
return time.time() - t1
def numpy_version():
t1 = time.time()
X = np.arange(10000000)
Y = np.arange(10000000)
Z = X + Y
return time.time() - t1
if __name__ == '__main__':
testing_numpy()
print(trad_version())
print(numpy_version())
'''
3.23564291
0.0714290142059
'''

10
ebook_src/USEFUL/basic_examples/example_open_files.py
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#!/usr/bin/env python
__author__ = "bt3"
filename = raw_input('Enter a file name: ')
try:
f = open(filename, "r")
except:
print 'There is no file named', filename

58
ebook_src/USEFUL/basic_examples/example_pickle.py
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#!/usr/bin/env python
__author__ = "bt3"
import pickle
def import_pickle(filename):
fh = None
try:
fh = open(filename, "rb")
mydict2 = pickle.load(fh)
return mydict2
except (EnvironmentError) as err:
print ("{0}: import error: {0}".format(os.path.basename(sys.arg[0]), err))
return false
finally:
if fh is not None:
fh.close()
def test_import_pickle():
pkl_file = 'test.dat'
mydict = import_pickle(pkl_file)
print(mydict)
def export_pickle(data, filename='test.dat', compress=False):
fh = None
try:
if compress:
fh = gzip.open(filename, "wb") # write binary
else:
fh = open(filename, "wb") # compact binary pickle format
pickle.dump(data, fh, pickle.HIGHEST_PROTOCOL)
except(EnvironmentError, pickle.PickingError) as err:
print("{0}: export error: {1}".format(os.path.basename(sys.argv[0], err)))
return False
finally:
if fh is not None:
fh.close()
def test_export_pickle():
mydict = {'a': 1, 'b': 2, 'c': 3}
export_pickle(mydict)
if __name__ == '__main__':
test_export_pickle()
test_import_pickle()

13
ebook_src/USEFUL/basic_examples/example_queue.py
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#!/usr/bin/env python
__author__ = "bt3"
import Queue
q = Queue.Queue()
for i in range(10):
q.put(i)
for i in range(10):
print q.get(i)

27
ebook_src/USEFUL/basic_examples/example_random.py
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#!/usr/bin/env python
__author__ = "bt3"
import random
def testing_random():
''' testing the module random'''
values = [1, 2, 3, 4]
print(random.choice(values))
print(random.choice(values))
print(random.choice(values))
print(random.sample(values, 2))
print(random.sample(values, 3))
''' shuffle in place '''
random.shuffle(values)
print(values)
''' create random integers '''
print(random.randint(0,10))
print(random.randint(0,10))
if __name__ == '__main__':
testing_random()

38
ebook_src/USEFUL/basic_examples/example_setdefault.py
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#!/usr/bin/env python
__author__ = "bt3"
def usual_dict(dict_data):
newdata = {}
for k, v in dict_data:
if k in newdata:
newdata[k].append(v)
else:
newdata[k] = [v]
return newdata
def setdefault_dict(dict_data):
newdata = {}
for k, v in dict_data:
newdata.setdefault(k, []).append(v)
return newdata
def test_setdef(module_name='this module'):
dict_data = (('key1', 'value1'),
('key1', 'value2'),
('key2', 'value3'),
('key2', 'value4'),
('key2', 'value5'),)
print(usual_dict(dict_data))
print(setdefault_dict(dict_data))
s = 'Tests in {name} have {con}!'
print(s.format(name=module_name, con='passed'))
if __name__ == '__main__':
test_setdef()

37
ebook_src/USEFUL/basic_examples/example_sets.py
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#!/usr/bin/env python
__author__ = "bt3"
def difference(l1):
""" return the list with duplicate elements removed """
return list(set(l1))
def intersection(l1, l2):
""" return the intersection of two lists """
return list(set(l1) & set(l2))
def union(l1, l2):
""" return the union of two lists """
return list(set(l1) | set(l2))
def test_sets_operations_with_lists():
l1 = [1,2,3,4,5,9,11,15]
l2 = [4,5,6,7,8]
l3 = []
assert(difference(l1) == [1, 2, 3, 4, 5, 9, 11, 15])
assert(difference(l2) == [8, 4, 5, 6, 7])
assert(intersection(l1, l2) == [4,5])
assert(union(l1, l2) == [1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 15])
assert(difference(l3) == [])
assert(intersection(l3, l2) == l3)
assert(sorted(union(l3, l2)) == sorted(l2))
print('Tests passed!')
if __name__ == '__main__':
test_sets_operations_with_lists()

35
ebook_src/USEFUL/basic_examples/example_socket.py
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#!/usr/bin/env python
__author__ = "bt3"
import socket
def netcat(hostname, port, content):
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((hostname, port))
s.sendall(content)
adata = []
while 1:
data = s.recv(1024)
if data == '':
break
adata.append(data)
s.close()
return adata
if __name__ == '__main__':
PORT = 12345
HOSTNAME = '54.209.5.48'
message = netcat(HOSTNAME, PORT, 'Hello!')[1]
print message

11
ebook_src/USEFUL/basic_examples/example_string_format.py
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#!/usr/bin/env python
__author__ = "bt3"
foo = 'foo'
bar = 'bar'
print '%s%s' % (foo, bar) # It is OK
print '{0}{1}'.format(foo, bar) # It is better
print '{foo}{bar}'.format(foo=foo, bar=bar) # It is best

8
ebook_src/USEFUL/basic_examples/example_subprocess.py
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#!/usr/bin/env python
__author__ = "bt3"
import subprocess,os
os.system('ls')
subprocess.call(['ls', '-1'], shell=True)

22
ebook_src/USEFUL/basic_examples/example_telnet.py
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#!/usr/bin/env python
__author__ = "bt3"
from telnetlib import Telnet
# examples of telnet connections
PORT = 12345
HOST = '54.209.5.48'
# creating connection
tn = Telnet(HOST ,PORT)
# reading input
msg_in2 = tn.read_all().dec_msg()
tn.read_until(b'psifer text: ')
# writing outputs
tn.write(msg.encode() + b'\n')

46
ebook_src/USEFUL/basic_examples/example_testing.py
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#!/usr/bin/env python
__author__ = "bt3"
def test_doctest():
'''
>>> 1 == 1
False
'''
pass
if __name__ == '__main__':
import doctest
doctest.testmod()
#####
import unittest
class BasicsTestCase(unittest.TestCase):
def test_find_name(self):
self.assertTrue(1 == 1)
self.assertFalse(1 == 2)
if __name__ == '__main__':
unittest.main()
#####
# content of test_example.py, run with $ py.test
#
# run tests over the directory
# $ nosetest
def func(x):
return x + 1
def test_answer():
assert func(3) == 4

16
ebook_src/USEFUL/basic_examples/example_threads.py
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#!/usr/bin/env python
__author__ = "bt3"
import threading
def worker(num):
"""thread worker function"""
print 'Worker: %s' % num
return
threads = []
for i in range(5):
t = threading.Thread(target=worker, args=(i,))
threads.append(t)
t.start()

24
ebook_src/USEFUL/basic_examples/example_time.py
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#!/usr/bin/python
__author__ = "bt3"
''' a simple example of how to time a function '''
import time
def sumOfN2(n):
start = time.time()
theSum = 0
for i in range(1,n+1):
theSum = theSum + i
end = time.time()
return theSum,end-start
if __name__ == '__main__':
n = 5
print("Sum is %d and required %10.7f seconds"%sumOfN2(n))
n = 200
print("Sum is %d and required %10.7f seconds"%sumOfN2(n))

0
ebook_src/USEFUL/dynamic_programming/__init__.py
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42
ebook_src/USEFUL/dynamic_programming/memo.py
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#!/usr/bin/python3
__author__ = "bt3"
from functools import wraps
from do_benchmark import benchmark
def memo(func):
''' an example of dynamic programming using a memoizing decorator '''
cache = {}
@wraps(func)
def wrap(*args):
if args not in cache:
cache[args] = func(*args)
return cache[args]
return wrap
@memo
def find_fibonacci_seq_rec(n):
''' implements the nth fibonacci value in a recursive exponential runtime '''
if n < 2: return n
return find_fibonacci_seq_rec(n - 1) + find_fibonacci_seq_rec(n - 2)
def test_memo():
n = 50
# find_fibonacci_seq_rec = memo(find_fibonacci_seq_rec)
# @benchmark
print(find_fibonacci_seq_rec(n))
if __name__ == '__main__':
test_memo()

85
ebook_src/USEFUL/dynamic_programming/memoized_longest_inc_subseq.py
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#!/usr/bin/python3
__author__ = "bt3"
from itertools import combinations
from bisect import bisect
from memo import memo
from do_benchmark import benchmark
def naive_longest_inc_subseq(seq):
''' naive (exponential) solution to the longest increasing subsequence problem '''
for length in range(len(seq), 0, -1):
for sub in combinations(seq, length):
if list(sub) == sorted(sub):
return len(sub)
def longest_inc_subseq1(seq):
''' an iterative algorithm for the longest increasing subsequence problem '''
end = []
for val in seq:
idx = bisect(end, val)
if idx == len(end): end.append(val)
else: end[idx] = val
return len(end)
def longest_inc_subseq2(seq):
''' another iterative algorithm for the longest increasing subsequence problem '''
L = [1] * len(seq)
for cur, val in enumerate(seq):
for pre in range(cur):
if seq[pre] <= val:
L[cur] = max(L[cur], 1 + L[pre])
return max(L)
def memoized_longest_inc_subseq(seq):
''' a memoized recursive solution to find the longest increasing subsequence problem '''
@memo
def L(cur):
res = 1
for pre in range(cur):
if seq[pre] <= seq[cur]:
res = max(res, 1 + L(pre))
return res
return max(L(i) for i in range(len(seq)))
@benchmark
def test_naive_longest_inc_subseq():
print(naive_longest_inc_subseq(s1))
benchmark
def test_longest_inc_subseq1():
print(longest_inc_subseq1(s1))
@benchmark
def test_longest_inc_subseq2():
print(longest_inc_subseq2(s1))
@benchmark
def test_memoized_longest_inc_subseq():
print(memoized_longest_inc_subseq(s1))
if __name__ == '__main__':
from random import randrange
s1 = [randrange(100) for i in range(25)]
print(s1)
test_naive_longest_inc_subseq()
test_longest_inc_subseq1()
test_longest_inc_subseq2()
test_memoized_longest_inc_subseq()

62
ebook_src/USEFUL/oop/ShapeClass.py
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#!/usr/bin/python3
# mari von steinkirch @2013
# steinkirch at gmail
import math
class Point(object):
def __init__(self, x=0, y=0): # self: object reference to the object itself
self.x = x # data attribute
self.y = y
def distance_from_origin(self):
return math.hypot(self.x, self.y)
def __eq__(self, other):
return self.x == other.x and self.y == other.y
def __repr__(self):
return "point ({0.x!r}, {0.y!r})".format(self)
def __str__(self): # cannot be passed to eval
return "({0.x!r}, {0.y!r})".format(self)
class Circle(Point):
def __init__(self, radius, x=0, y=0):
super().__init__(x,y) # creates and initializes self.x and self.y
self.radius = radius
def edge_distance_from_origin(self):
return abs(self.distance_from_origin() - self.radius)
def area(self):
return math.pi*(self.radius**2)
def circumference(self):
return 2*math.pi*self.radius
def __eq__(self, other): # let us avoid infinite recursion
return self.radius == other.radius and super().__eq__(other)
def __repr__(self):
return "circle ({0.radius!r}, {0.x!r})".format(self)
def __str__(self):
return repr(self)
if __name__ == '__main__':
a = Point(3,4)
print(a.distance_from_origin())
c = Circle(3,2,1)
print(c)
print(c.circumference())
print(c. edge_distance_from_origin())

0
ebook_src/USEFUL/oop/__init__.py
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30
ebook_src/USEFUL/useful_with_files/change_ext_file.py
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#!/usr/bin/env python
__author__ = "bt3"
import os
import sys
import shutil
def change_file_ext():
""" read a file and an extension from the command line and produces a copy with its extension changed"""
if len(sys.argv) < 2:
print("Usage: change_ext.py filename.old_ext 'new_ext'")
sys.exit()
name = os.path.splitext(sys.argv[1])[0] + "." + sys.argv[2]
print (name)
try:
shutil.copyfile(sys.argv[1], name)
except OSError as err:
print (err)
if __name__ == '__main__':
change_file_ext()

28
ebook_src/USEFUL/useful_with_files/count_unique_words_files.py
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#!/usr/bin/python
__author__ = "bt3"
import collections
import string
import sys
def count_unique_word_file():
if len(sys.argv) < 2:
print "Usage: python count_unique_word.py NAMEFILE"
words = collections.defaultdict(int)
strip = string.whitespace + string.punctuation + string.digits + "\"'"
for filename in sys.argv[1:]:
with open(filename) as file:
for line in file:
for word in line.lower().split():
word = word.strip(strip)
if len(word) > 2:
words[word] = +1
for word in sorted(words):
print("'{0}' occurs {1} times.".format(word, words[word]))
if __name__ == '__main__':
count_unique_word_file()

15
ebook_src/USEFUL/useful_with_files/count_unique_words_frequency.py
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@ -1,15 +0,0 @@
#!/usr/bin/python
__author__ = "bt3"
import collections
import sys
def count_unique_word_freq():
return collections.Counter(\
sys.stdin.read().lower().split()).most_common(n)
if __name__ == '__main__':
count_unique_word_freq()

27
ebook_src/USEFUL/useful_with_files/grep_word_from_files.py
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@ -1,27 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
import sys
def grep_word_from_files():
''' using iterator enumerate to create a grep command '''
word = sys.argv[1]
for filename in sys.argv[2:]:
with open(filename) as file:
for lino, line in enumerate(file, start=1):
if word in line:
print("{0}:{1}:{2:.40}".format(filename, lino, line.rstrip()))
if __name__ == '__main__':
if len(sys.argv) < 2:
print("Usage: grep_word_from_files.py word infile1 [infile2...]")
sys.exit()
else:
grep_word_from_files()

54
ebook_src/USEFUL/useful_with_files/remove_blank_lines.py
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@ -1,54 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
import os
import sys
def read_data(filename):
lines = []
fh = None
try:
fh = open(filename)
for line in fh:
if line.strip():
lines.append(line)
except (IOError, OSError) as err:
print(err)
finally:
if fh is not None:
fh.close()
return lines
def write_data(lines, filename):
fh = None
try:
fh = open(filename, "w")
for line in lines:
fh.write(line)
except (EnvironmentError) as err:
print(err)
finally:
if fh is not None:
fh.close()
def remove_blank_lines():
""" read a list of filenames on the command line and for each one produces another file with the same content but with no blank lines """
if len(sys.argv) < 2:
print ("Usage: noblank.py infile1 [infile2...]")
for filename in sys.argv[1:]:
lines = read_data(filename)
if lines:
write_data(lines, filename)
if __name__ == '__main__':
remove_blank_lines()

41
ebook_src/abstract_structures/HashTable.py
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@ -1,41 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
class HashTable(object):
def __init__(self, slots=10):
self.slots = slots
self.table = []
self.create_table()
def hash_key(self, value):
return hash(value)%self.slots
def create_table(self):
for i in range(self.slots):
self.table.append([])
def add_item(self, value):
key = self.hash_key(value)
self.table[key].append(value)
def print_table(self):
for key in range(len(self.table)):
print "Key is %s, value is %s." %(key, self.table[key])
def find_item(self, item):
pos = self.hash_key(item)
if item in self.table[pos]:
return True
else:
return False
if __name__ == '__main__':
dic = HashTable(5)
for i in range(1, 40, 2):
dic.add_item(i)
dic.print_table()
assert(dic.find_item(20) == False)
assert(dic.find_item(21) == True)

47
ebook_src/abstract_structures/Queue.py
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@ -1,47 +0,0 @@
#!/usr/bin/env python
# Time: 5 min
__author__ = "bt3"
class Queue(object):
def __init__(self):
self.enq = []
self.deq = []
def enqueue(self, item):
return self.enq.append(item)
def deque(self):
if not self.deq:
while self.enq:
self.deq.append(self.enq.pop())
return self.deq.pop()
def peak(self):
if not self.deq:
while self.enq:
self.deq.append(self.enq.pop())
if self.deq:
return self.deq[-1]
def size(self):
return len(self.enq) + len(self.deq)
def isempty(self):
return not (self.enq + self.deq)
if __name__ == '__main__':
q = Queue()
for i in range(1,11):
q.enqueue(i)
print 'Size:', q.size()
print 'Is empty?', q.isempty()
print 'Peak: ', q.peak()
print
print 'Dequeuing...'
for i in range(10):
print q.deque()
print 'Size:', q.size()
print 'Is empty?', q.isempty()
print 'Peak: ', q.peak()

63
ebook_src/abstract_structures/Stack.py
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@ -1,63 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
class Stack(object):
def __init__(self):
self.content = []
self.min_array = []
self.min = float('inf')
def push(self, value):
if value < self.min:
self.min = value
self.content.append(value)
self.min_array.append(self.min)
def pop(self):
if self.content:
value = self.content.pop()
self.min_array.pop()
if self.min_array:
self.min = self.min_array[-1]
return value
else:
return 'Empty List. '
def find_min(self):
if self.min_array:
return self.min_array[-1]
else:
return 'No min value for empty list.'
def size(self):
return len(self.content)
def isEmpty(self):
return not bool(self.content)
def peek(self):
if self.content:
return self.content[-1]
else:
print('Stack is empty.')
def __repr__(self):
return '{}'.format(self.content)
if __name__ == '__main__':
q = Stack()
for i in range(15,20):
q.push(i)
for i in range(10,5,-1):
q.push(i)
for i in range(1, 13):
print q.pop(), q.find_min()

1
ebook_src/abstract_structures/__init__.py
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@ -1 +0,0 @@
__all__=["hash_tables", "heap", "linked_list", "queues", "stacks"]

0
ebook_src/abstract_structures/heap/__init__.py
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51
ebook_src/abstract_structures/heap/find_N_largest_smallest_items_seq.py
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@ -1,51 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
import heapq
def find_N_largest_items_seq(seq, N):
''' find the N largest items in a sequence '''
return heapq.nlargest(N,seq)
def find_N_smallest_items_seq(seq, N):
''' find the N smallest items in a sequence '''
return heapq.nsmallest(N, seq)
def find_smallest_items_seq_heap(seq):
''' find the smallest items in a sequence using heapify first'''
''' heap[0] is always the smallest item '''
''' pops the smallest item, O(logN) '''
heapq.heapify(seq)
return heapq.heappop(seq)
def find_smallest_items_seq(seq):
''' if it is only one item, min() is faster '''
return min(seq)
def find_N_smallest_items_seq_sorted(seq, N):
''' N ~ len(seq), better sort instead'''
return sorted(seq)[:N]
def find_N_largest_items_seq_sorted(seq, N):
''' N ~ len(seq), better sort instead'''
return sorted(seq)[len(seq)-N:]
def test_find_N_largest_smallest_items_seq(module_name='this module'):
seq = [1, 3, 2, 8, 6, 10, 9]
N = 3
assert(find_N_largest_items_seq(seq, N) == [10, 9, 8])
assert(find_N_largest_items_seq_sorted(seq, N) == [8, 9, 10])
assert(find_N_smallest_items_seq(seq, N) == [1,2,3])
assert(find_N_smallest_items_seq_sorted(seq, N) == [1,2,3])
assert(find_smallest_items_seq(seq) == 1)
assert(find_smallest_items_seq_heap(seq) == 1)
s = 'Tests in {name} have {con}!'
print(s.format(name=module_name, con='passed'))
if __name__ == '__main__':
test_find_N_largest_smallest_items_seq()

49
ebook_src/abstract_structures/heap/heapify.py
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@ -1,49 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
class Heapify(object):
def __init__(self, data=None):
self.data = data or []
for i in range(len(data)//2, -1, -1):
self.__max_heapify__(i)
def __repr__(self):
return '{}'.format(self.data)
def parent(self, i):
return i >> 1
def left_child(self, i):
return (i << 1) + 1
def right_child(self, i):
return (i << 1) + 2 # +2 instead of +1 because it's 0-indexed.
def __max_heapify__(self, i):
largest = i
left = self.left_child(i)
right = self.right_child(i)
n = len(self.data)
largest = (left < n and self.data[left] > self.data[i]) and left or i
largest = (right < n and self.data[right] > self.data[largest]) and right or largest
if i is not largest:
self.data[i], self.data[largest] = self.data[largest], self.data[i]
self.__max_heapify__(largest)
def extract_max(self):
n = len(self.data)
max_element = self.data[0]
self.data[0] = self.data[n - 1]
self.data = self.data[:n - 1]
self.__max_heapify__(0)
return max_element
def test_Heapify():
l1 = [3, 2, 5, 1, 7, 8, 2]
h = Heapify(l1)
assert(h.extract_max() == 8)
if __name__ == '__main__':
test_Heapify()

27
ebook_src/abstract_structures/heap/merge_sorted_seqs.py
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@ -1,27 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
import heapq
def merge_sorted_seq(seq1, seq2):
''' merge two sorted sequences with little ovehead. the result
will be sorted, which is different of doing just +'''
result = []
for c in heapq.merge(seq1, seq2):
result.append(c)
return result
def test_merge_sorted_seq(module_name='this module'):
seq1 = [1, 2, 3, 8, 9, 10]
seq2 = [2, 3, 4, 5, 6, 7, 9]
seq3 = seq1 + seq2
assert(merge_sorted_seqseq1, seq2) == sorted(seq3))
if __name__ == '__main__':
test_merge_sorted_seq()

40
ebook_src/abstract_structures/heap/priority_queue.py
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@ -1,40 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
import heapq
class PriorityQueue(object):
''' implements a priority queue class '''
def __init__(self):
self._queue = []
self._index = 0 # comparying same priority level
def push(self, item, priority):
heapq.heappush(self._queue, (-priority, self._index, item))
self._index += 1
def pop(self):
return heapq.heappop(self._queue)[-1]
class Item:
def __init__(self, name):
self.name = name
def __repr__(self):
return "Item({!r})".format(self.name)
def test_PriorityQueue():
''' push and pop are all O(logN) '''
q = PriorityQueue()
q.push(Item('test1'), 1)
q.push(Item('test2'), 4)
q.push(Item('test3'), 3)
assert(str(q.pop()) == "Item('test2')")
if __name__ == '__main__':
test_PriorityQueue()

0
ebook_src/abstract_structures/linked_list/__init__.py
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55
ebook_src/abstract_structures/linked_list/circular_ll.py
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@ -1,55 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
''' implement a function to see whether a linked list is circular.
To implement this, we just need two pointers with different
paces (for example, one goes twice faster)'''
from linked_list_fifo import LinkedListFIFO
from node import Node
class cicularLinkedListFIFO(LinkedListFIFO):
def _add(self, value):
self.length += 1
node = Node(value, self.head)
if self.tail:
self.tail.pointer = node
self.tail = node
def isCircularll(ll):
p1 = ll.head
p2 = ll.head
while p2:
try:
p1 = p1.pointer
p2 = p2.pointer.pointer
except:
break
if p1 == p2:
return True
return False
if __name__ == '__main__':
ll = LinkedListFIFO()
for i in range(10):
ll.addNode(i)
ll._printList()
print(isCircularll(ll))
lcirc = cicularLinkedListFIFO()
for i in range(10):
lcirc.addNode(i)
print(isCircularll(lcirc))

81
ebook_src/abstract_structures/linked_list/double_linked_list_fifo.py
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@ -1,81 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
''' Implement a double-linked list, which is very simple, we just need inherits
from a Linked List Class and add an attribute for previous.'''
from linked_list_fifo import LinkedListFIFO
class dNode(object):
def __init__(self, value=None, pointer=None, previous=None):
self.value = value
self.pointer = pointer
self.previous = previous
class dLinkList(LinkedListFIFO):
def printListInverse(self):
node = self.tail
while node:
print(node.value)
try:
node = node.previous
except:
break
def _add(self, value):
self.length += 1
node = dNode(value)
if self.tail:
self.tail.pointer = node
node.previous = self.tail
self.tail = node
def _delete(self, node):
self.length -= 1
node.previous.pointer = node.pointer
if not node.pointer:
self.tail = node.previous
def _find(self, index):
node = self.head
i = 0
while node and i < index:
node = node.pointer
i += 1
return node, i
# delete nodes in general
def deleteNode(self, index):
if not self.head or not self.head.pointer:
self._deleteFirst()
else:
node, i = self._find(index)
if i == index:
self._delete(node)
else:
print('Node with index {} not found'.format(index))
if __name__ == '__main__':
from collections import Counter
ll = dLinkList()
for i in range(1, 5):
ll.addNode(i)
print('Printing the list...')
ll._printList()
print('Now, printing the list inversely...')
ll.printListInverse()
print('The list after adding node with value 15')
ll._add(15)
ll._printList()
print("The list after deleting everything...")
for i in range(ll.length-1, -1, -1):
ll.deleteNode(i)
ll._printList()

42
ebook_src/abstract_structures/linked_list/find_kth_from_the_end.py
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@ -1,42 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
''' Find the mth-to-last element of a linked list.
One option is having two pointers, separated by m. P1 start at the roots
(p1 = self.root) and p2 is m-behinf pointer, which is created when p1 is at m.
When p1 reach the end, p2 is the node. '''
from linked_list_fifo import LinkedListFIFO
from node import Node
class LinkedListFIFO_find_kth(LinkedListFIFO):
def find_kth_to_last(self, k):
p1, p2 = self.head, self.head
i = 0
while p1:
if i > k:
try:
p2 = p2.pointer
except:
break
p1 = p1.pointer
i += 1
return p2.value
if __name__ == '__main__':
ll = LinkedListFIFO_find_kth()
for i in range(1, 11):
ll.addNode(i)
print('The Linked List:')
print(ll._printList())
k = 3
k_from_last = ll.find_kth_to_last(k)
print("The %dth element to the last of the LL of size %d is %d" %(k, ll.length, k_from_last))

90
ebook_src/abstract_structures/linked_list/linked_list_fifo.py
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@ -1,90 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
''' A class for a linked list that has the nodes in a FIFO order (such as a queue)'''
from node import Node
class LinkedListFIFO(object):
def __init__(self):
self.head = None
self.length = 0
self.tail = None # this is different from ll lifo
def _printList(self):
node = self.head
while node:
print(node.value)
node = node.pointer
def _addFirst(self, value):
self.length = 1
node = Node(value)
self.head = node
self.tail = node
def _deleteFirst(self):
self.length = 0
self.head = None
self.tail = None
print('The list is empty.')
def _add(self, value):
self.length += 1
node = Node(value)
if self.tail:
self.tail.pointer = node
self.tail = node
def addNode(self, value):
if not self.head:
self._addFirst(value)
else:
self._add(value)
def _find(self, index):
prev = None
node = self.head
i = 0
while node and i < index:
prev = node
node = node.pointer
i += 1
return node, prev, i
def deleteNode(self, index):
if not self.head or not self.head.pointer:
self._deleteFirst()
else:
node, prev, i = self._find(index)
if i == index and node:
self.length -= 1
if i == 0 or not prev :
self.head = node.pointer
else:
prev.pointer = node.pointer
if not self.tail == node:
self.tail = prev
else:
print('Node with index {} not found'.format(index))
if __name__ == '__main__':
ll = LinkedListFIFO()
for i in range(1, 5):
ll.addNode(i)
print('The list is:')
ll._printList()
print('The list after deleting node with index 2:')
ll.deleteNode(2)
ll._printList()
print('The list after adding node with value 15')
ll._add(15)
ll._printList()
print("The list after deleting everything...")
for i in range(ll.length-1, -1, -1):
ll.deleteNode(i)
ll._printList()

90
ebook_src/abstract_structures/linked_list/linked_list_lifo.py
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@ -1,90 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
''' Implement a unordered linked list, i.e. a LIFO linked list (like a stack) '''
from node import Node
class LinkedListLIFO(object):
def __init__(self):
self.head = None
self.length = 0
def _printList(self):
node = self.head
while node:
print(node.value)
node = node.pointer
def _delete(self, prev, node):
self.length -= 1
if not prev:
self.head = node.pointer
else:
prev.pointer = node.pointer
def _add(self, value):
self.length += 1
self.head = Node(value, self.head)
def _find(self, index):
prev = None
node = self.head
i = 0
while node and i < index:
prev = node
node = node.pointer
i += 1
return node, prev, i
def _find_by_value(self, value):
prev = None
node = self.head
found = 0
while node and not found:
if node.value == value:
found = True
else:
prev = node
node = node.pointer
return node, prev, found
def deleteNode(self, index):
node, prev, i = self._find(index)
if index == i:
self._delete(prev, node)
else:
print('Node with index {} not found'.format(index))
def deleteNodeByValue(self, value):
node, prev, found = self._find_by_value(value)
if found:
self._delete(prev, node)
else:
print('Node with value {} not found'.format(value))
if __name__ == '__main__':
ll = LinkedListLIFO()
for i in range(1, 5):
ll._add(i)
print('The list is:')
ll._printList()
print('The list after deleting node with index 2:')
ll.deleteNode(2)
ll._printList()
print('The list after deleting node with value 3:')
ll.deleteNodeByValue(2)
ll._printList()
print('The list after adding node with value 15')
ll._add(15)
ll._printList()
print("The list after deleting everything...")
for i in range(ll.length-1, -1, -1):
ll.deleteNode(i)
ll._printList()

33
ebook_src/abstract_structures/linked_list/node.py
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@ -1,33 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
class Node(object):
def __init__(self, value=None, pointer=None):
self.value = value
self.pointer = pointer
def getData(self):
return self.value
def getNext(self):
return self.pointer
def setData(self, newdata):
self.value = newdata
def setNext(self, newpointer):
self.pointer = newpointer
if __name__ == '__main__':
L = Node("a", Node("b", Node("c", Node("d"))))
assert(L.pointer.pointer.value=='c')
print(L.getData())
print(L.getNext().getData())
L.setData('aa')
L.setNext(Node('e'))
print(L.getData())
print(L.getNext().getData())

57
ebook_src/abstract_structures/linked_list/part_linked_list.py
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@ -1,57 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
''' This function divides a linked list in a value, where everything smaller than this value
goes to the front, and everything large goes to the back:'''
from linked_list_fifo import LinkedListFIFO
from node import Node
def partList(ll, n):
more = LinkedListFIFO()
less = LinkedListFIFO()
node = ll.head
while node:
item = node.value
if item < n:
less.addNode(item)
elif item > n:
more.addNode(item)
node = node.pointer
less.addNode(n)
nodemore = more.head
while nodemore:
less.addNode(nodemore.value)
nodemore = nodemore.pointer
return less
if __name__ == '__main__':
ll = LinkedListFIFO()
l = [6, 7, 3, 4, 9, 5, 1, 2, 8]
for i in l:
ll.addNode(i)
print('Before Part')
ll._printList()
print('After Part')
newll = partList(ll, 6)
newll._printList()

85
ebook_src/abstract_structures/linked_list/sum_linked_list.py
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@ -1,85 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
''' Supposing two linked lists representing numbers, such that in each of their
nodes they carry one digit. This function sums the two numbers that these
two linked lists represent, returning a third list representing the sum:'''
from linked_list_fifo import LinkedListFIFO
from node import Node
class LinkedListFIFOYield(LinkedListFIFO):
# print each node's value, starting from the head
def _printList(self):
node = self.head
while node:
yield(node.value)
node = node.pointer
def sumlls(l1, l2):
lsum = LinkedListFIFOYield()
dig1 = l1.head
dig2 = l2.head
pointer = 0
while dig1 and dig2:
d1 = dig1.value
d2 = dig2.value
sum_d = d1 + d2 + pointer
if sum_d > 9:
pointer = sum_d//10
lsum.addNode(sum_d%10)
else:
lsum.addNode(sum_d)
pointer = 0
dig1 = dig1.pointer
dig2 = dig2.pointer
if dig1:
sum_d = pointer + dig1.value
if sum_d > 9:
lsum.addNode(sum_d%10)
else:
lsum.addNode(sum_d)
dig1 = dig1.pointer
if dig2:
sum_d = pointer + dig2.value
if sum_d > 9:
lsum.addNode(sum_d%10)
else:
lsum.addNode(sum_d)
dig2 = dig2.pointer
return lsum
if __name__ == '__main__':
l1 = LinkedListFIFOYield() # 2671
l1.addNode(1)
l1.addNode(7)
l1.addNode(6)
l1.addNode(2)
l2 = LinkedListFIFOYield() # 455
l2.addNode(5)
l2.addNode(5)
l2.addNode(4)
lsum = sumlls(l1, l2)
l = list(lsum._printList())
for i in reversed(l):
print i

0
ebook_src/abstract_structures/queues/__init__.py
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109
ebook_src/abstract_structures/queues/animal_shelter.py
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@ -1,109 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
""" A class for an animal shelter with two queues"""
class Node(object):
def __init__(self, animalName=None, animalKind=None, pointer=None):
self.animalName = animalName
self.animalKind = animalKind
self.pointer = pointer
self.timestamp = 0
class AnimalShelter(object):
def __init__(self):
self.headCat = None
self.headDog = None
self.tailCat = None
self.tailDog = None
self.animalNumber = 0
# Queue any animal
def enqueue(self, animalName, animalKind):
self.animalNumber += 1
newAnimal = Node(animalName, animalKind)
newAnimal.timestamp = self.animalNumber
if animalKind == 'cat':
if not self.headCat:
self.headCat = newAnimal
if self.tailCat:
self.tailCat.pointer = newAnimal
self.tailCat = newAnimal
elif animalKind == 'dog':
if not self.headDog:
self.headDog = newAnimal
if self.tailDog:
self.tailDog.pointer = newAnimal
self.tailDog = newAnimal
# Dequeue methods
def dequeueDog(self):
if self.headDog:
newAnimal = self.headDog
self.headDog = newAnimal.pointer
return str(newAnimal.animalName)
else:
return 'No Dogs!'
def dequeueCat(self):
if self.headCat:
newAnimal = self.headCat
self.headCat = newAnimal.pointer
return str(newAnimal.animalName)
else:
return 'No Cats!'
def dequeueAny(self):
if self.headCat and not self.headDog:
return self.dequeueCat()
elif self.headDog and not self.headCat:
return self.dequeueDog()
elif self.headDog and self.headCat:
if self.headDog.timestamp < self.headCat.timestamp:
return self.dequeueDog()
else:
return self.dequeueCat()
else:
return ('No Animals!')
def _print(self):
print("Cats:")
cats = self.headCat
while cats:
print(cats.animalName, cats.animalKind)
cats = cats.pointer
print("Dogs:")
dogs = self.headDog
while dogs:
print(dogs.animalName, dogs.animalKind)
dogs = dogs.pointer
if __name__ == '__main__':
qs = AnimalShelter()
qs.enqueue('bob', 'cat')
qs.enqueue('mia', 'cat')
qs.enqueue('yoda', 'dog')
qs.enqueue('wolf', 'dog')
qs._print()
print("Deque one dog and one cat...")
qs.dequeueDog()
qs.dequeueCat()
qs._print()

39
ebook_src/abstract_structures/queues/deque.py
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#!/usr/bin/env python
__author__ = "bt3"
''' a class for a double ended queue (also inefficient) '''
from queue import Queue
class Deque(Queue):
def enqueue_back(self, item):
self.items.append(item)
def dequeue_front(self):
return self.items.pop(0)
if __name__ == '__main__':
queue = Deque()
print("Is the queue empty? ", queue.isEmpty())
print("Adding 0 to 10 in the queue...")
for i in range(10):
queue.enqueue(i)
print("Queue size: ", queue.size())
print("Queue peek : ", queue.peek())
print("Dequeue...", queue.dequeue())
print("Queue peek: ", queue.peek())
print("Is the queue empty? ", queue.isEmpty())
print(queue)
print("\nNow using the dequeue methods...")
print("Dequeue from front...", queue.dequeue_front())
print("Queue peek: ", queue.peek())
print(queue)
print("Queue from back...")
queue.enqueue_back(50)
print("Queue peek: ", queue.peek())
print(queue)

80
ebook_src/abstract_structures/queues/linked_queue.py
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@ -1,80 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
''' Queue acts as a container for nodes (objects) that are inserted and removed according FIFO'''
class Node(object):
def __init__(self, value=None, pointer=None):
self.value = value
self.pointer = None
class LinkedQueue(object):
def __init__(self):
self.head = None
self.tail = None
def isEmpty(self):
return not bool(self.head)
def dequeue(self):
if self.head:
value = self.head.value
self.head = self.head.pointer
return value
else:
print('Queue is empty, cannot dequeue.')
def enqueue(self, value):
node = Node(value)
if not self.head:
self.head = node
self.tail = node
else:
if self.tail:
self.tail.pointer = node
self.tail = node
def size(self):
node = self.head
num_nodes = 0
while node:
num_nodes += 1
node = node.pointer
return num_nodes
def peek(self):
return self.head.value
def _print(self):
node = self.head
while node:
print(node.value)
node = node.pointer
if __name__ == '__main__':
queue = LinkedQueue()
print("Is the queue empty? ", queue.isEmpty())
print("Adding 0 to 10 in the queue...")
for i in range(10):
queue.enqueue(i)
print("Is the queue empty? ", queue.isEmpty())
queue._print()
print("Queue size: ", queue.size())
print("Queue peek : ", queue.peek())
print("Dequeue...", queue.dequeue())
print("Queue peek: ", queue.peek())
queue._print()

47
ebook_src/abstract_structures/queues/palindrome_checker_with_deque.py
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#!/usr/bin/env python
__author__ = "bt3"
""" Using our deque class and Python's deque class """
import string
import collections
from deque import Deque
STRIP = string.whitespace + string.punctuation + "\"'"
def palindrome_checker_with_deque(str1):
d1 = Deque()
d2 = collections.deque()
for s in str1.lower():
if s not in STRIP:
d2.append(s)
d1.enqueue(s)
eq1 = True
while d1.size() > 1 and eq1:
if d1.dequeue_front() != d1.dequeue():
eq1 = False
eq2 = True
while len(d2) > 1 and eq2:
if d2.pop() != d2.popleft():
eq2 = False
return eq1, eq2
if __name__ == '__main__':
str1 = 'Madam Im Adam'
str2 = 'Buffy is a Slayer'
print(palindrome_checker_with_deque(str1))
print(palindrome_checker_with_deque(str2))

63
ebook_src/abstract_structures/queues/queue.py
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@ -1,63 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
class Queue(object):
def __init__(self):
self.in_stack = []
self.out_stack = []
def _transfer(self):
while self.in_stack:
self.out_stack.append(self.in_stack.pop())
def enqueue(self, item):
return self.in_stack.append(item)
def dequeue(self):
if not self.out_stack:
self._transfer()
if self.out_stack:
return self.out_stack.pop()
else:
return "Queue empty!"
def size(self):
return len(self.in_stack) + len(self.out_stack)
def peek(self):
if not self.out_stack:
self._transfer()
if self.out_stack:
return self.out_stack[-1]
else:
return "Queue empty!"
def __repr__(self):
if not self.out_stack:
self._transfer()
if self.out_stack:
return '{}'.format(self.out_stack)
else:
return "Queue empty!"
def isEmpty(self):
return not (bool(self.in_stack) or bool(self.out_stack))
if __name__ == '__main__':
queue = Queue()
print("Is the queue empty? ", queue.isEmpty())
print("Adding 0 to 10 in the queue...")
for i in range(10):
queue.enqueue(i)
print("Queue size: ", queue.size())
print("Queue peek : ", queue.peek())
print("Dequeue...", queue.dequeue())
print("Queue peek: ", queue.peek())
print("Is the queue empty? ", queue.isEmpty())
print("Printing the queue...")
print(queue)

0
ebook_src/abstract_structures/stacks/__init__.py
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30
ebook_src/abstract_structures/stacks/dec2bin_with_stack.py
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#!/usr/bin/env python
__author__ = "bt3"
'''transform a decimal number to a binary number with a stack '''
from stack import Stack
def dec2bin_with_stack(decnum):
s = Stack()
str_aux = ''
while decnum > 0:
dig = decnum % 2
decnum = decnum//2
s.push(dig)
while not s.isEmpty():
str_aux += str(s.pop())
return str_aux
if __name__ == '__main__':
decnum = 9
assert(dec2bin_with_stack(decnum) == '1001')

71
ebook_src/abstract_structures/stacks/linked_stack.py
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@ -1,71 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
""" A stack made of linked list"""
class Node(object):
def __init__(self, value=None, pointer=None):
self.value = value
self.pointer = pointer
class Stack(object):
def __init__(self):
self.head = None
def isEmpty(self):
return not bool(self.head)
def push(self, item):
self.head = Node(item, self.head)
def pop(self):
if self.head:
node = self.head
self.head = node.pointer
return node.value
else:
print('Stack is empty.')
def peek(self):
if self.head:
return self.head.value
else:
print('Stack is empty.')
def size(self):
node = self.head
count = 0
while node:
count +=1
node = node.pointer
return count
def _printList(self):
node = self.head
while node:
print(node.value)
node = node.pointer
if __name__ == '__main__':
stack = Stack()
print("Is the stack empty? ", stack.isEmpty())
print("Adding 0 to 10 in the stack...")
for i in range(10):
stack.push(i)
stack._printList()
print("Stack size: ", stack.size())
print("Stack peek : ", stack.peek())
print("Pop...", stack.pop())
print("Stack peek: ", stack.peek())
print("Is the stack empty? ", stack.isEmpty())
stack._printList()

31
ebook_src/abstract_structures/stacks/reverse_string_with_stack.py
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@ -1,31 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
''' Uses a stack to reverse a string '''
from stack import Stack
def reverse_string_with_stack(str1):
s = Stack()
revStr = ''
for c in str1:
s.push(c)
while not s.isEmpty():
revStr += s.pop()
return revStr
if __name__ == '__main__':
str1 = 'Buffy is a Slayer!'
print(str1)
print(reverse_string_with_stack(str1))

56
ebook_src/abstract_structures/stacks/set_of_stacks.py
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@ -1,56 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
""" define a class for a set of stacks """
from stack import Stack
class SetOfStacks(Stack):
def __init__(self, capacity=4):
self.setofstacks = []
self.items = []
self.capacity = capacity
def push(self, value):
if self.size() >= self.capacity:
self.setofstacks.append(self.items)
self.items = []
self.items.append(value)
def pop(self):
value = self.items.pop()
if self.isEmpty() and self.setofstacks:
self.items = self.setofstacks.pop()
return value
def sizeStack(self):
return len(self.setofstacks)*self.capacity + self.size()
def __repr__(self):
aux = []
for s in self.setofstacks:
aux.extend(s)
aux.extend(self.items)
return '{}'.format(aux)
if __name__ == '__main__':
capacity = 5
stack = SetOfStacks(capacity)
print("Is the stack empty? ", stack.isEmpty())
print("Adding 0 to 10 in the stack...")
for i in range(10):
stack.push(i)
print(stack)
print("Stack size: ", stack.sizeStack())
print("Stack peek : ", stack.peek())
print("Pop...", stack.pop())
print("Stack peek: ", stack.peek())
print("Is the stack empty? ", stack.isEmpty())
print(stack)

65
ebook_src/abstract_structures/stacks/stack.py
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@ -1,65 +0,0 @@
#!/usr/bin/env python
# copy of the class ../Stack.py
__author__ = "bt3"
class Stack(object):
def __init__(self):
self.content = []
self.min_array = []
self.min = float('inf')
def push(self, value):
if value < self.min:
self.min = value
self.content.append(value)
self.min_array.append(self.min)
def pop(self):
if self.content:
value = self.content.pop()
self.min_array.pop()
if self.min_array:
self.min = self.min_array[-1]
return value
else:
return 'Empty List. '
def find_min(self):
if self.min_array:
return self.min_array[-1]
else:
return 'No min value for empty list.'
def size(self):
return len(self.content)
def isEmpty(self):
return not bool(self.content)
def peek(self):
if self.content:
return self.content[-1]
else:
print('Stack is empty.')
def __repr__(self):
return '{}'.format(self.content)
if __name__ == '__main__':
q = Stack()
for i in range(15,20):
q.push(i)
for i in range(10,5,-1):
q.push(i)
for i in range(1, 13):
print q.pop(), q.find_min()

77
ebook_src/abstract_structures/stacks/stack_with_min.py
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@ -1,77 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
''' A stack with a minimum lookup '''
from stack import Stack
class NodeWithMin(object):
def __init__(self, value=None, minimum=None):
self.value = value
self.minimum = minimum
class StackMin(Stack):
def __init__(self):
self.items = []
self.minimum = None
def push(self, value):
if self.isEmpty() or self.minimum > value:
self.minimum = value
self.items.append(NodeWithMin(value, self.minimum))
def peek(self):
return self.items[-1].value
def peekMinimum(self):
return self.items[-1].minimum
def pop(self):
item = self.items.pop()
if item:
if item.value == self.minimum:
self.minimum = self.peekMinimum()
return item.value
else:
print("Stack is empty.")
def __repr__(self):
aux = []
for i in self.items:
aux.append(i.value)
return '{}'.format(aux)
if __name__ == '__main__':
stack = StackMin()
print("Is the stack empty? ", stack.isEmpty())
print("Adding 0 to 10 in the stack...")
for i in range(10,3, -1):
stack.push(i)
print(stack)
print("Stack size: ", stack.size())
print("Stack peek and peekMinimum : ", stack.peek(), stack.peekMinimum())
print("Pop...", stack.pop())
print("Stack peek and peekMinimum : ", stack.peek(), stack.peekMinimum())
print("Is the stack empty? ", stack.isEmpty())
print(stack)
for i in range(5, 1, -1):
stack.push(i)
print(stack)
print("Stack size: ", stack.size())
print("Stack peek and peekMinimum : ", stack.peek(), stack.peekMinimum())
print("Pop...", stack.pop())
print("Stack peek and peekMinimum : ", stack.peek(), stack.peekMinimum())
print("Is the stack empty? ", stack.isEmpty())
print(stack)

41
ebook_src/abstract_structures/stacks/towers_of_hanoi.py
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@ -1,41 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
""" Implement the 'towers of hanoi'"""
from linked_stack import Stack, Node
def moveTop(s1, s3):
s3.append(s1.pop())
def moveDisks(n, s1, s3, s2):
if n < 1: return
moveDisks(n - 1, s1, s2, s3)
moveTop(s1, s3)
moveDisks(n -1, s2, s3, s1)
def towersOfHanoi(n):
s1 = [x+1 for x in range(n)]
s2 = []
s3 = []
print('The first stick is {0} and the third stick has {1}'.format(s1, s3))
moveDisks(n, s1, s3, s2)
print('The first stick is {0} and the third stick has {1}'.format(s1, s3))
return s3
if __name__ == '__main__':
towersOfHanoi(6)

28
ebook_src/bitwise/bit_array.py
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@ -1,28 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
''' Example of how to use a bit array in python as a "counter" dict'''
def print_dupl_ba(l1):
'''
>>> l1 = [0, 1, 2, 3, 4, 2, 6, 7, 8, 9]
>>> print_dupl_ba(l1)
2
'''
bs = bytearray(10)
for i in range(len(l1)):
if i == l1[i]:
bs[i] = 1
for index, bit in enumerate(bs):
if bit == 0:
return l1[index]
return None
if __name__ == '__main__':
import doctest
doctest.testmod()

33
ebook_src/bitwise/bitwise.txt
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@ -1,33 +0,0 @@
BIT-WISE
----------------------
1. To find a number:
11000101 is 2^0+2^2+2^6+2^7 = 197
2. Left shifting:
0010 1011 << 4 ---> 1011 000
3. Right shifting:
0010 1011 >> 4 ---> 0000 0010
or it can be filled with the copy of the first bit, instead of 0:
1011 0010 >> 4 ---> 1111 1011
4. XOR can cancels out:
15 ^ 12 ^ 15 = 12
5. 2^x:
left-shift 1 by x:
0000 0001 << x
so if x = 2, 2^2 = 4 -> 100
0000 0001 << 2 ---> 0000 0100
6. Is power of 2?
just do x&(x-1).
if 0 --> yes!

37
ebook_src/bitwise/clear_bits.py
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@ -1,37 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
''' Clear a bit in a binary number.
Like the reverse of set bit:
1) first create a number filled of 1s,
with 0 at i (can create 0001000 and ~)
2) AND the number so it clears the ith bit
'''
def clear_bit(num, i):
mask = ~ (1 << i) # -0b10001
return bin(num & mask)
def clear_all_bits_from_i_to_0(num, i):
mask = ~ ( (1 << (i+1)) - 1)
return bin(num & mask)
def clear_all_bits_from_most_sig_to_1(num, i):
mask = ( 1 << i) -1
return bin(num & mask)
if __name__ == '__main__':
num = int('10010000', 2)
print clear_bit(num, 4) # '0b10000000'
num = int('10010011', 2)
print clear_all_bits_from_i_to_0(num, 2) # '0b10010000'
num = int('1110011', 2)
print clear_all_bits_from_most_sig_to_1(num, 2) #'0b11'

25
ebook_src/bitwise/find_bit_len.py
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@ -1,25 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
''' Find how many bits a int has:
1) Start with a mask of 1
2) Mask with AND
3) if result (if true): count += 1
(obs: to find the int of a bin do int('1001', 2)) and to show in bin
do bin(int))
'''
def find_bit_len(int_num):
lenght = 0
while int_num:
int_num >>= 1
lenght += 1
return lenght
if __name__ == '__main__':
for i in range(17):
print(find_bit_len(i))
print i.bit_length()

32
ebook_src/bitwise/find_how_many_1_binary.py
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@ -1,32 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
''' Find how many 1s in the binary:
1) Start with a mask of 1
2) Mask with AND
3) if result (if true): count += 1
(obs: to find the int of a bin do int('1001',
2)) and to show in bin do bin(int))
'''
def find_how_many_1_in_a_binary(n):
'''
>>> find_how_many_1_in_a_binary(9)
2
'''
counter = 0
while n:
if n & 1:
counter += 1
n >>= 1
return counter
if __name__ == '__main__':
import doctest
doctest.testmod()

27
ebook_src/bitwise/get_bit.py
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@ -1,27 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
''' Get a bit in a binary number:
1) Shifts 1 over by i bits
2) make an AND with the number
3) all the other than the bit at i are clean, now compare to 0
4) if the new value is not 0, bit i is 1
'''
def get_bit(num, i):
mask = 1 << i
return num & mask != 0
if __name__ == '__main__':
num = int('0100100', 2)
get_bit(num, 0) # 0
get_bit(num, 1) # 0
get_bit(num, 2) # 1
get_bit(num, 3) # 0
get_bit(num, 4) # 0
get_bit(num, 5) # 1
get_bit(num, 6) # 0

37
ebook_src/bitwise/get_float_rep_bin.py
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@ -1,37 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
''' Given a real number between 0 and 1 (eg: 0.72), this method print the binary
representation. If the Number cannot be represented accurately in binary, with at
most 32 chars, print error:
'''
def get_float_rep(num):
'''
>>> get_float_rep(0.72)
('Error 2', '.1011100001010001111010111000010')
>>> get_float_rep(0.1)
('Error 2', '.0001100110011001100110011001100')
>>> get_float_rep(0.5)
'.1'
'''
if num >= 1 or num <= 0: return 'Error 1'
result = '.'
while num:
if len(result) >= 32: return 'Error 2', result
r = num*2
if r >= 1:
result += '1'
num = r - 1
else:
result += '0'
num = r
return result
if __name__ == '__main__':
import doctest
doctest.testmod()

36
ebook_src/bitwise/insert_small_bin_into_big_bin.py
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@ -1,36 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
''' Given two 32-bit numbers, N and M, and two bit positions, i and j, this
method insert M into N such that M starts at bit j and ends at bit i:
1) clear the bits j thru i in N'
2) shift M so that it lines up with bits j thru i
3) merge M and N
'''
def insert_small_bin_into_big_bin(M, N, i, j):
'''
>>> N = 0b10000000000
>>> M = 0b10011
>>> j = 6
>>> i = 2
>>> insert_small_bin_into_big_bin(M, N, i, j)
'0b10001001100'
'''
allOnes = ~0
left = allOnes << (j+1) # 1110000
right = ( (1 << i) - 1) # 0000111
mask = left | right # 1110111
N_cleared = N & mask
M_shifted = M << i
return bin( N_cleared | M_shifted)
if __name__ == '__main__':
import doctest
doctest.testmod()

59
ebook_src/bitwise/next_with_same_num_1s.py
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@ -1,59 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
''' Give a positive int, print the next smallest and next largest ints with
same number of 1 bits.
The brute force is:
1) find number of 1 bits
2) loop above and down until find same, checking for each
'''
def print_prev_same_1s(num):
n1s = find_num_1s(num)
# find prev
i = num-1
while True:
n1s_here = find_num_1s(i)
if n1s_here == n1s:
return bin(i)
i -= 1
if i < 0:
return None
def print_next_same_1s(num):
n1s = find_num_1s(num)
# find next
i = num+1
while True:
n1s_here = find_num_1s(i)
if n1s_here == n1s:
return bin(i)
i += 1
if i < 0:
return None
def find_num_1s(num):
counter = 0
while num:
if num & 1:
counter += 1
num >>= 1
return counter
if __name__ == '__main__':
num = 0b1001
n = '0b1010'
p = '0b110'
print_prev_same_1s(num) == p
print_next_same_1s(num) == n

40
ebook_src/bitwise/num_bits_to_convert_2_nums.py
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@ -1,40 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
''' This method returns the number of bits that are necessary to change to convert two
numbers A and B:
1) XOR
2) count 1s
'''
def count_bits_swap2(a, b):
count = 0
m = a^b
while m:
count +=1
m = m & (m-1)
return count
def count_bits_swap(a, b):
m = a^b
return count_1s(m)
def count_1s(m):
count = 0
while m:
if m& 1 :
count +=1
m >>= 1
return count
if __name__ == '__main__':
a = int('10010000', 2)
b = int('01011010', 2)
print count_bits_swap(a, b) #4
print count_bits_swap2(a, b) #4

26
ebook_src/bitwise/set_bit.py
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@ -1,26 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
''' Set a bit in a binary number:
1) Shifts 1 over by i bits
2) make an OR with the number, only the value at bit i will change and all the others bit
of the mask are zero so will not affect the num
'''
def set_bit(num, i):
mask = 1 << i
return bin( num | mask )
if __name__ == '__main__':
num = int('0100100', 2)
print set_bit(num, 0) #'0b100101'
print set_bit(num, 1) #'0b100110'
print set_bit(num, 2) # nothing change '0b100100'
print set_bit(num, 3) #'0b101100'
print set_bit(num, 4) #'0b110100'
print set_bit(num, 5) # nothing change '0b100100'

23
ebook_src/bitwise/swap_in_place.py
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@ -1,23 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
'''
swapping values in place without extra memory
'''
def swap_bit(a, b):
'''
>>> swap_bit(14, 73)
(73, 14)
'''
a = a^b
b = a^b
a = a^b
return a, b
if __name__ == '__main__':
import doctest
doctest.testmod()

37
ebook_src/bitwise/swap_odd_even.py
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@ -1,37 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
''' Swap odd and even bits in a smart way in a binary:
1) first for odds, take n and move the odd:
(a) Mask all odd bits with 10101010 (0xAA)
(b) shift by right by 1
2) do the same to ints with 01010101
3) merge
'''
def swap_odd_even(num):
'''
>>> num = 0b11011101
>>> result = '0b1101110'
>>> swap_odd_even(num) == result
True
'''
mask_odd = 0xAA # 0b10101010
mask_even = 0x55 # 0b1010101
odd = num & mask_odd
odd >>= 1
even = num & mask_even
even >>= 1
return bin(odd | even)
if __name__ == '__main__':
import doctest
doctest.testmod()

22
ebook_src/bitwise/update_bit.py
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@ -1,22 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
''' This method merges set bit and clean bit:
1) first clear the bit at i using a mask such as 1110111
2) then shift the intended value v by i bits
3) this will create a number with bit i to v and all other to 0
4) finally update the ith bit with or
'''
def update_bit(num, i, v):
mask = ~ (1 << i)
return bin( (num & mask) | (v << i) )
if __name__ == '__main__':
num = int('10010000', 2)
print update_bit(num, 2, 1) # '0b10010100'

0
ebook_src/builtin_structures/__init__.py
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51
ebook_src/builtin_structures/anagram.py
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@ -1,51 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
from collections import Counter
def is_anagram(s1, s2):
'''
>>> is_anagram('cat', 'tac')
True
>>> is_anagram('cat', 'hat')
False
'''
counter = Counter()
for c in s1:
counter[c] += 1
for c in s2:
counter[c] -= 1
for i in counter.values():
if i:
return False
return True
''' verify if words are anagrams by comparing a sum of Unicode code
point of the character'''
def get_unicode_sum(word):
s = 0
for p in word:
s += ord(p)
return s
def is_anagram2(word1, word2):
'''
>>> is_anagram2('cat', 'tac')
True
>>> is_anagram2('cat', 'hat')
False
'''
return get_unicode_sum(word1) == get_unicode_sum(word2)
if __name__ == '__main__':
import doctest
doctest.testmod()

9
ebook_src/builtin_structures/balance.txt
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@ -1,9 +0,0 @@
__author__ = "bt3"
This is the classic "you have 8 balls/coins, which are the same weight, except for one which is slightly heavier than the others. You also have an old-style balance. What is the fewest number of weighings to find the heavy coin/ball?
Answer: 2! You need to use every information available:
Weight 3 x 3 balls/coins.
If they weight the same: weight the 2 balls/coins left outside.
Else, measure 2 of the 3 heavier balls/coins.

40
ebook_src/builtin_structures/balance_symbols.py
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@ -1,40 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
'''
Given a N different open and close braces in a string "( { [ } ] )".
How do you check whether the string has matching braces.
'''
from collections import Counter
def check_if_balance(string):
'''
>>> check_if_balance('{[[(])}]')
True
>>> check_if_balance('{[[()}]')
False
>>> check_if_balance('')
True
'''
table = Counter()
for i in string:
index = str(ord(i))[0]
if i in '{[(':
table[index] += 1
elif i in ')}]':
table[index] -= 1
for i in table.values():
if i !=-0:
return False
return True
if __name__ == '__main__':
import doctest
doctest.testmod()

71
ebook_src/builtin_structures/check_if_2_numbers_sum_to_k.py
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@ -1,71 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
"""
Given an integer x and an unsorted array of integers, describe an
algorithm to determine whether two of the numbers add up to x.
1. Using hash tables.
2. Sorting the array and keeping two pointers in the array, one in
the beginning and one in the end. Whenever the sum of the current
two integers is less than x, move the first pointer forwards, and
whenever the sum is greater than x, move the second pointer
backwards. O(nln n).
3. Create a BST with x minus each element in the array.
Check whether any element of the array appears in the BST.
It takes O(nlog n) times two.
"""
from collections import defaultdict, Counter
def check_sum(array, k):
'''
>>> check_sum([3, 2, 6, 7, 9, 1], 8)
[(6, 2), (1, 7)]
>>> check_sum([5, 2, 6, 7, 9, 1], 4)
[]
>>>
'''
dict = defaultdict()
res = []
for i in array:
if k-i in dict:
res.append((i, k-i))
del dict[k-i]
else:
dict[i] = 1
return res
def check_sum2(array, k):
'''
>>> check_sum2([1, 4, 2, 7, 1, 3, 10, 15, 3, 1], 6)
set([(3, 3)])
>>> check_sum2([1, 4, 2, 7, 1, 3, 10, 15, 3, 1], 0)
set([])
'''
dict = Counter()
res = set()
for i in array:
dict[i] += 1
for i in array:
if dict[k-i] > 0:
if i == k-i and dict[k-i] > 1:
res.add((i, k-i))
dict[k-i] -= 2
elif i == k-i:
res.add((i, k-i))
dict[k-i] -= 1
return res
if __name__ == '__main__':
import doctest
doctest.testmod()

36
ebook_src/builtin_structures/check_if_3_numbers_sum_to_zero.py
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@ -1,36 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
''' Determine if an Array of integers contains 3 numbers that sum to 0 '''
from collections import defaultdict
def find_3_number(array):
'''
>>> find_3_number([1,5,56,11,-3,-12])
1 11 -12
True
>>> find_3_number([] )
False
'''
hash_ = defaultdict()
for i in array:
hash_[i] = 1
for i, x in enumerate(array):
for y in array[i+1:]:
if -(x+y) in hash_:
print x, y, -(x+y)
return True
return False
if __name__ == '__main__':
import doctest
doctest.testmod()

35
ebook_src/builtin_structures/check_non_overlapping_intervals.py
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@ -1,35 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
'''
given an array of intervals, return max number of non-overlapping intervals
'''
from collections import defaultdict
def non_overlapping(array):
'''
>>> non_overlapping([(1,2), (2,5), (1, 6)])
[[(1, 2), (2, 5)]]
>>> non_overlapping([(1,4), (2,5), (3, 6)])
[]
'''
total = []
for i, t in enumerate(array):
start = t[0]
end = t[1]
for tt in array[i+1:] :
if end <= tt[0]:
total.append([(start, end), (tt[0], tt[1])])
return total
if __name__ == '__main__':
import doctest
doctest.testmod()

64
ebook_src/builtin_structures/convert_numerical_bases.py
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@ -1,64 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
''' convert an integer to a string in any base'''
def convert_from_dec_to_any_base(number, base):
'''
>>> number, base = 9, 2
>>> convert_from_dec_to_any_base(number, base)
'1001'
'''
convertString = '012345679ABCDEF'
if number < base:
return convertString[number]
else:
return convert_from_dec_to_any_base(number//base, base) + \
convertString[number%base]
def convert_from_decimal_to_binary(number, base):
'''
>>> number, base = 9, 2
>>> convert_from_decimal_to_binary(number, base)
1001
'''
multiplier, result = 1, 0
while number > 0:
result += number%base*multiplier
multiplier *= 10
number = number//base
return result
def convert_from_decimal_larger_bases(number, base):
'''
>>> number, base = 31, 16
>>> convert_from_decimal_larger_bases(number, base)
'1F'
'''
strings = "0123456789ABCDEFGHIJ"
result = ""
while number > 0:
digit = number%base
result = strings[digit] + result
number = number//base
return result
if __name__ == '__main__':
import doctest
doctest.testmod()

83
ebook_src/builtin_structures/convert_str_2_int.py
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@ -1,83 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
def conv_int2str(int1):
'''
>>> conv_str2int('367')
367
>>> conv_str2int('0')
0
>>> conv_str2int('-10')
-10
>>> conv_str2int('1e5')
100000
'''
aux_dict = {key:value for key in range(10) for value in '0123456789'[key]}
if int1 == 0:
return '0'
elif int1 < 0:
sign = '-'
int1 = int1*(-1)
else:
sign = ''
aux_ls = []
while int1 > 0:
c = int1%10
int1 = int1//10
cadd = aux_dict[c]
aux_ls.append(cadd)
aux_ls.reverse()
return sign + ''.join(aux_ls)
def conv_str2int(str1):
'''
>>> conv_int2str(0)
'0'
>>> conv_int2str(1e5)
'100000'
>>> conv_int2str(367)
'367'
>>> conv_int2str(-10)
'-10'
'''
if not str1:
return None
aux_dict = {key:value for value in range(10) for key in '0123456789'[value]}
if str1[0] == '-':
sign = -1
str1 = str1[1:]
else:
sign = 1
dec, result = 1, 0
for i in range(len(str1)-1, -1, -1):
aux = str1[i]
if aux == 'e':
exp_num = conv_str2int(str1[i+1:])
number = conv_str2int(str1[:i])
result = number*10**exp_num
break
result += aux_dict[aux]*dec
dec *= 10
return result*sign
if __name__ == '__main__':
import doctest
doctest.testmod()

26
ebook_src/builtin_structures/count_unique_words_On2.py
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@ -1,26 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
import collections
import string
import sys
def count_unique_word():
words = collections.defaultdict(int)
strip = string.whitespace + string.punctuation + string.digits + "\"'"
for filename in sys.argv[1:]:
with open(filename) as file:
for line in file:
for word in line.lower().split():
word = word.strip(strip)
if len(word) > 2:
words[word] = +1
for word in sorted(words):
print("'{0}' occurs {1} times.".format(word, words[word]))

49
ebook_src/builtin_structures/delete_duplicate_char_str.py
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@ -1,49 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
''' find and delete all the duplicate characters in a string '''
from collections import Counter
def delete_unique(str1):
'''
>>> delete_unique("Trust no one")
'on'
>>> delete_unique("Mulder?")
''
'''
str_strip = ''.join(str1.split())
repeat = Counter()
for c in str_strip:
repeat[c] += 1
result = ''
for c, count in repeat.items():
if count > 1:
result += c
return result
def removing_duplicates_seq(str1):
'''
>>> delete_unique("Trust no one")
'on'
>>> delete_unique("Mulder?")
''
'''
seq = str1.split()
result = set()
for item in seq:
if item not in result:
#yield item
result.add(item)
return result
if __name__ == '__main__':
import doctest
doctest.testmod()

60
ebook_src/builtin_structures/fibonacci.py
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@ -1,60 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
def fib_generator():
a, b = 0, 1
while True:
yield b
a, b = b, a+b
def fib(n):
'''
>>> fib(2)
1
>>> fib(5)
5
>>> fib(7)
13
'''
if n < 3:
return 1
a, b = 0, 1
count = 1
while count < n:
count += 1
a, b = b, a+b
return b
def fib_rec(n):
'''
>>> fib_rec(2)
1
>>> fib_rec(5)
5
>>> fib_rec(7)
13
'''
if n < 3:
return 1
return fib_rec(n - 1) + fib_rec(n - 2)
if __name__ == '__main__':
import doctest
doctest.testmod()
fib = fib_generator()
print(next(fib))
print(next(fib))
print(next(fib))
print(next(fib))

35
ebook_src/builtin_structures/find_0_MxN_replace_cols_rows.py
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@ -1,35 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
def find_0_MxN(m):
''' find 0s in a matrix and replace the col and row to 0s:
>>> m1 = [[1,2,3,4], [5,6,7,8], [9,10,11,12], [13,14,15,16]]
>>> find_0_MxN(m1)
[[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12], [13, 14, 15, 16]]
>>> m2 = [[1, 2, 3, 4], [0, 6, 7, 8], [9, 10, 11, 12], [13, 14, 15, 16]]
>>> find_0_MxN(m2)
[[0, 2, 3, 4], [0, 0, 0, 0], [0, 10, 11, 12], [0, 14, 15, 16]]
'''
index = []
for row in range(len(m)):
for col in range(len(m[0])):
if m[row][col] == 0:
index.append((row, col))
for i in index:
row = i[0]
col = i[1]
for i in range(len(m)):
m[row][i] = 0
for i in range(len(m[0])):
m[i][col] = 0
return m
if __name__ == '__main__':
import doctest
doctest.testmod()

32
ebook_src/builtin_structures/find_dice_probabilities.py
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@ -1,32 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
'''
given 2 dice, determine number of ways to sum S if all dice are rolled
'''
from collections import Counter, defaultdict
def find_dice_probabilities(S=5, n_faces=6):
if S > 2*n_faces or S < 2:
return None
cdict = Counter()
ddict = defaultdict(list)
for dice1 in range(1, n_faces+1):
for dice2 in range(1, n_faces+1):
t = [dice1, dice2]
cdict[dice1+dice2] += 1
ddict[dice1+dice2].append( t)
return [cdict[S], ddict[S]]
if __name__ == '__main__':
results = find_dice_probabilities()
assert(results[0] == len(results[1]))

43
ebook_src/builtin_structures/find_edit_distance.py
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@ -1,43 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
''' computes the edit distance between two strings '''
def find_edit_distance(str1, str2):
'''
>>> s = 'sunday'
>>> t = 'saturday'
>>> find_edit_distance(s, t)
3
'''
m = len(str1)
n = len(str2)
diff = lambda c1, c2: 0 if c1 == c2 else 1
E = [[0] * (n + 1) for i in range(m + 1)]
for i in range(m + 1):
E[i][0] = i
for j in range(1, n + 1):
E[0][j] = j
for i in range(1, m + 1):
for j in range(1, n + 1):
E[i][j] = min(E[i-1][j] + 1, E[i][j-1] + 1, E[i-1][j-1] + diff(str1[i-1], str2[j-1]))
return E[m][n]
if __name__ == '__main__':
import doctest
doctest.testmod()

29
ebook_src/builtin_structures/find_first_non_repetead_char.py
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@ -1,29 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
from collections import Counter
def find_non_rep_char(s1):
'''
>>> s1 = 'aabbcceff'
>>> find_non_rep_char(s1)
e
>>> find_non_rep_char('ccc')
'''
aux_dict = Counter()
for i in s1:
aux_dict[i] += 1
for k, v in aux_dict.items():
if v < 2:
print k
if __name__ == '__main__':
import doctest
doctest.testmod()

29
ebook_src/builtin_structures/find_gcd.py
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@ -1,29 +0,0 @@
#!/usr/bin/env python
__author__ = "bt3"
def finding_gcd(a, b):
''' implements the greatest common divider algorithm '''
while(b != 0):
result = b
a, b = b, a % b
return result
def test_finding_gcd():
number1 = 21
number2 = 12
assert(finding_gcd(number1, number2) == 3)
print('Tests passed!')
if __name__ == '__main__':
test_finding_gcd()

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