bitwise scripts fixed

This commit is contained in:
Mari Wahl 2015-01-06 21:55:53 -05:00
parent 01703751f1
commit 91825867f6
25 changed files with 96 additions and 335 deletions

View File

@ -1,17 +1,16 @@
#!/usr/bin/python3
# mari von steinkirch @2013
# steinkirch at gmail
#!/usr/bin/env python
''' Example of how to use a bit array in python as a "counter" dict:
__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
'''
'''
def print_dupl_ba(l1):
bs = bytearray(10)
for i in range(len(l1)):
if i == l1[i]:
@ -23,9 +22,6 @@ def print_dupl_ba(l1):
if __name__ == '__main__':
import doctest
doctest.testmod()

View File

@ -1,40 +0,0 @@
#!/usr/bin/python3
# mari von steinkirch @2013
# steinkirch at gmail
''' Clear a bit in a binary number. It is almost 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
>>> num = int('10010000', 2)
>>> clear_bit(num, 4)
'0b10000000'
>>> num = int('10010011', 2)
>>> clear_all_bits_from_i_to_0(num, 2)
'0b10010000'
>>> num = int('1110011', 2)
>>> clear_all_bits_from_most_sig_to_1(num, 2)
'0b11'
'''
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__':
import doctest
doctest.testmod()

View File

@ -1,28 +0,0 @@
#!/usr/bin/python3
# mari von steinkirch @2013
# steinkirch at gmail
''' 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))
>>> for i in range(17): print(find_bit_len(i))
'''
def find_bit_len(int_num):
lenght = 0
while int_num:
int_num >>= 1
lenght += 1
return lenght
if __name__ == '__main__':
import doctest
doctest.testmod()

View File

@ -1,41 +0,0 @@
#!/usr/bin/python3
# mari von steinkirch @2013
# steinkirch at gmail
''' 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
>>> 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
'''
def get_bit(num, i):
mask = 1 << i
return num & mask != 0
if __name__ == '__main__':
import doctest
doctest.testmod()

View File

@ -1,45 +0,0 @@
#!/usr/bin/python3
# mari von steinkirch @2013
# steinkirch at gmail
''' This method returns the number of bits that are necessary to change to convert two
numbers A and B:
1) XOR
2) count 1s
>>> a = int('10010000', 2)
>>> b = int('01011010', 2)
>>> count_bits_swap(a, b)
4
>>> count_bits_swap2(a, b)
4
'''
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__':
import doctest
doctest.testmod()

View File

@ -1,38 +0,0 @@
#!/usr/bin/python3
# mari von steinkirch @2013
# steinkirch at gmail
''' 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
>>> num = int('0100100', 2)
>>> set_bit(num, 0)
'0b100101'
>>> set_bit(num, 1)
'0b100110'
>>> set_bit(num, 2) # nothing change
'0b100100'
>>> set_bit(num, 3)
'0b101100'
>>> set_bit(num, 4)
'0b110100'
>>> set_bit(num, 5) # nothing change
'0b100100'
'''
def set_bit(num, i):
mask = 1 << i
return bin( num | mask )
if __name__ == '__main__':
import doctest
doctest.testmod()

View File

@ -1,26 +0,0 @@
#!/usr/bin/python3
# mari von steinkirch @2013
# steinkirch at gmail
''' 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
>>> num = int('10010000', 2)
>>> update_bit(num, 2, 1)
'0b10010100'
'''
def update_bit(num, i, v):
mask = ~ (1 << i)
return bin( (num & mask) | (v << i) )
if __name__ == '__main__':
import doctest
doctest.testmod()

View File

@ -6,7 +6,8 @@ __author__ = "bt3"
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))
(obs: to find the int of a bin do int('1001', 2)) and to show in bin
do bin(int))
'''
@ -22,4 +23,3 @@ if __name__ == '__main__':
for i in range(17):
print(find_bit_len(i))
print i.bit_length()
print

View File

@ -1,21 +1,22 @@
#!/usr/bin/python3
# mari von steinkirch @2013
# steinkirch at gmail
#!/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))
>>> find_how_many_1_in_a_binary(9)
2
(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:
@ -25,9 +26,6 @@ def find_how_many_1_in_a_binary(n):
if __name__ == '__main__':
import doctest
doctest.testmod()

View File

@ -1,20 +1,22 @@
#!/usr/bin/python3
# mari von steinkirch @2013
# steinkirch at gmail
#!/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'
'''
'''
def get_float_rep(num):
if num >= 1 or num <= 0: return 'Error 1'
result = '.'
while num:

View File

@ -1,22 +1,25 @@
#!/usr/bin/python3
# mari von steinkirch @2013
# steinkirch at gmail
#!/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'
'''
'''
def insert_small_bin_into_big_bin(M, N, i, j):
allOnes = ~0
left = allOnes << (j+1) # 1110000
right = ( (1 << i) - 1) # 0000111
@ -27,8 +30,6 @@ def insert_small_bin_into_big_bin(M, N, i, j):
return bin( N_cleared | M_shifted)
if __name__ == '__main__':
import doctest
doctest.testmod()

View File

@ -1,21 +1,13 @@
#!/usr/bin/python3
# mari von steinkirch @2013
# steinkirch at gmail
#!/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
>>> num = 0b1001
>>> next = '0b1010'
>>> prev = '0b110'
>>> print_prev_same_1s(num) == prev
True
>>> print_next_same_1s(num) == next
True
'''
@ -59,6 +51,9 @@ def find_num_1s(num):
if __name__ == '__main__':
import doctest
doctest.testmod()
num = 0b1001
n = '0b1010'
p = '0b110'
print_prev_same_1s(num) == p
print_next_same_1s(num) == n

View File

@ -8,18 +8,14 @@ __author__ = "bt3"
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'

View File

@ -8,6 +8,10 @@ __author__ = "bt3"
def swap_bit(a, b):
'''
>>> swap_bit(14, 73)
(73, 14)
'''
a = a^b
b = a^b
a = a^b
@ -15,7 +19,5 @@ def swap_bit(a, b):
if __name__ == '__main__':
a = 14
b = 73
a2, b2 = swap_bit(a, b)
print "a was {0}, now it is {1}. \nb was {2}, now it is {3}".format(a, a2, b, b2)
import doctest
doctest.testmod()

View File

@ -1,6 +1,7 @@
#!/usr/bin/python3
# mari von steinkirch @2013
# steinkirch at gmail
#!/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:
@ -8,17 +9,18 @@
(b) shift by right by 1
2) do the same to ints with 01010101
3) merge
>>> num = 0b11011101
>>> result = '0b1101110'
>>> swap_odd_even(num) == result
True
'''
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
@ -29,9 +31,6 @@ def swap_odd_even(num):
if __name__ == '__main__':
import doctest
doctest.testmod()

View File

@ -1,8 +1,6 @@
#!/usr/bin/python
__author__ = "Mari Wahl"
__email__ = "marina.w4hl@gmail.com"
#!/usr/bin/env python
__author__ = "bt3"
def bubble_sort(seq):

View File

@ -1,7 +1,6 @@
#!/usr/bin/python
#!/usr/bin/env python
__author__ = "Mari Wahl"
__email__ = "marina.w4hl@gmail.com"
__author__ = "bt3"

View File

@ -1,8 +1,6 @@
#!/usr/bin/python
__author__ = "Mari Wahl"
__email__ = "marina.w4hl@gmail.com"
#!/usr/bin/env python
__author__ = "bt3"
def gnome_sort(seq):

View File

@ -1,7 +1,6 @@
#!/usr/bin/python
#!/usr/bin/env python
__author__ = "Mari Wahl"
__email__ = "marina.w4hl@gmail.com"
__author__ = "bt3"
class Heap(object):

View File

@ -1,7 +1,6 @@
#!/usr/bin/python
#!/usr/bin/env python
__author__ = "Mari Wahl"
__email__ = "marina.w4hl@gmail.com"
__author__ = "bt3"
''' Heapsort using Pythons libraries'''

View File

@ -1,7 +1,6 @@
#!/usr/bin/python
#!/usr/bin/env python
__author__ = "Mari Wahl"
__email__ = "marina.w4hl@gmail.com"
__author__ = "bt3"

View File

@ -1,7 +1,7 @@
#!/usr/bin/python
#!/usr/bin/env python
__author__ = "bt3"
__author__ = "Mari Wahl"
__email__ = "marina.w4hl@gmail.com"

View File

@ -1,7 +1,6 @@
#!/usr/bin/python
#!/usr/bin/env python
__author__ = "Mari Wahl"
__email__ = "marina.w4hl@gmail.com"
__author__ = "bt3"
''' Some examples of how to implement Quick Sort in Python

View File

@ -1,7 +1,6 @@
#!/usr/bin/python
#!/usr/bin/env python
__author__ = "Mari Wahl"
__email__ = "marina.w4hl@gmail.com"
__author__ = "bt3"
def selection_sort(seq):

View File

@ -1,7 +1,7 @@
#!/usr/bin/python
#!/usr/bin/env python
__author__ = "bt3"
__author__ = "Mari Wahl"
__email__ = "marina.w4hl@gmail.com"
''' A method to sort an array so that all the anagrams are together. Since we only
want the anagrams to be grouped, we can use a dictionary for this task. This