Merge branch 'master' of https://github.com/mariwahl/Over-100-Exercises-Python-and-Algorithms

.gitignore

@@ -34,3 +34,6 @@ nosetests.xml
 .mr.developer.cfg
 .project
 .pydevproject
+
+# PyCharm
+.idea

src/examples_in_my_book/sorting/bubble_sort.py

@@ -1,10 +1,19 @@
 #!/usr/bin/python3
-# mari von steinkirch @2013
+
-# steinkirch at gmail
+#  Mari von Steinkirch @ 2013
+# mari.wahl9@gmail.com
+
+# Bernardo Sulzbach (mafagafo) @ 2014
+# 1449441@gmail.com
 
 
 def bubble_sort(seq):
-    ''' implement bubble sort, a O(n^2) not efficient algorithm'''
+    """
+    Implementation of bubble sort.
+    O(n²) and thus highly ineffective.
+    :param seq: the sequence to be sorted.
+    :return: the sorted sequence.
+    """
     size = len(seq) -1
     for num in range(size, 0, -1):
         for i in range(num):
@@ -13,7 +22,6 @@ def bubble_sort(seq):
                 seq[i] = seq[i+1]
                 seq[i+1] = temp
     return seq
-    
 
 
 def test_bubble_sort(module_name='this module'):

src/further_examples/arrays_and_strings/reverse_str.py

@@ -1,26 +1,63 @@
 #!/usr/bin/python3
-# mari von steinkirch @2013
-# steinkirch at gmail
 
-   
+#  Mari von Steinkirch @ 2013
-def reverse_str(s):
+# mari.wahl9@gmail.com
-    ''' in place '''
+
-    sr_ls = []
+# Bernardo Sulzbach (mafagafo) @ 2014
-    for i in range(len(s)-1, -1, -1):
+# 1449441@gmail.com
-        sr_ls.append(s[i])
+
-    return ''.join(sr_ls)
+# This file defines and compares four different functions that reverse a string.
-        
+
+# timeit is used for benchmarking.
+from timeit import timeit
 
 
+def reverse_1(string):
+    """
+    Slowest function. Use a list and str.join to reverse the string.
+    :param string: the string to be reversed.
+    :return: a reversed string.
+    """
+    reversed_string = []
+    # Iterates from the last to the first character.
+    for i in range(len(string) - 1, -1, -1):
+        # Appends the character to the list.
+        reversed_string.append(string[i])
+    return ''.join(reversed_string)
 
-def main():
-    s1 = 'abcdefg'
-    s2 = 'buffy'
-    s3 = ''
-    print(reverse_str(s1))
-    print(reverse_str(s2))
-    print(reverse_str(s3))
-                   
-if __name__ == '__main__':
-    main()
 
+def reverse_2(string):
+    """
+    Same principle as reverse_1. One-liner cousin.
+    :param string: the string to be reversed.
+    :return: a reversed string.
+    """
+    return ''.join([character for character in [string[i] for i in range(len(string) - 1, -1, -1)]])
+
+
+def reverse_3(string):
+    """
+    Another one-liner. We make a list from the characters of the string and reverse it.
+    :param string: the string to be reversed.
+    :return: a reversed string.
+    """
+    return ''.join([character for character in string][::-1])
+
+# Overkill of elegance. A bit too passionate but it defines this lambda function well.
+# Simply returns the string backwards. As fast as concise.
+reverse_lambda = lambda s: s[::-1]
+
+# We define some short strings to test our functions.
+strings = ('buffy', 'foo', 'bar')
+# We announce what we are doing.
+print(', '.join(strings), ' should appear reversed if the function is working.\n')
+print('{:<30}:'.format('Function name'), 'benchmarking result (lower is better):')
+# Iterate over a tuple of functions.
+for function in (reverse_1, reverse_2, reverse_3, reverse_lambda):
+    name = function.__name__ if function.__name__ != "<lambda>" else 'reverse_lambda'
+    # We print the function's name and its benchmark result.
+    print("{:<30}:".format(name), timeit(name + "('string')", setup='from __main__ import ' + name))
+    # We print the output so that we can check if the function is working as expected.
+    print(', '.join(map(function, strings)), '\n')
+# We wait until the user wants to quit.
+input('Press Return to quit.')

src/further_examples/arrays_and_strings/reverse_words.py

@@ -0,0 +1,45 @@
+#!/usr/bin/python3
+
+# Mari von Steinkirch @ 2013
+# mari.wahl9@gmail.com
+
+# Bernardo Sulzbach (mafagafo) @ 2014
+# 1449441@gmail.com
+
+
+def reverse_words(string):
+    """
+    Reverse the order of the words in a sentence.
+    :param string: the string which words wil lbe reversed.
+    :return: the reversed string.
+    """
+    l1 = string.split(' ')
+    l1.reverse()
+    return ' '.join(l1)
+
+
+def reverse_words_brute(string):
+    """
+    Reverse the order of the words in a sentence.
+    :param string: the string which words wil lbe reversed.
+    :return: the reversed string.
+    """
+    word, sentence = [], []
+    for character in string:
+        if character != ' ':
+            word.append(character)
+        else:
+            # So we do not keep multiple whitespaces. An empty list evaluates to False.
+            if word:
+                sentence.append(''.join(word))
+            word = []
+    # So we do not keep multiple whitespaces. An empty list evaluates to False.
+    if word != '':
+        sentence.append(''.join(word))
+    sentence.reverse()
+    return ' '.join(sentence)
+
+if __name__ == '__main__':
+    phrase = 'I love  Google,   Fedora  & Python!'
+    print(reverse_words(phrase))
+    print(reverse_words_brute(phrase))

src/further_examples/arrays_and_strings/reverse_words_setence.py

@@ -1,44 +0,0 @@
-#!/usr/bin/python3
-# mari von steinkirch @2013
-# steinkirch at gmail
-
-''' reverse words in a setence, keeping the words right 
-   >>> str1 = 'I love Google and Python!'
-   >>> reverse_words(str1)
-   'Python! and Google love I'
-   >>> reverse_words('bla')
-   'bla'
-   >>> reverse_words('')
-   ''
-   >>> reverse_words_brute(str1)
-   'Python! and Google love I'
-   >>> reverse_words_brute('bla')
-   'bla'
-   >>> reverse_words_brute('')
-   ''
-'''
-
-def reverse_words(str1):
-    l1 = str1.split(' ')
-    l1.reverse()
-    return ' '.join(l1)
-    
-def reverse_words_brute(str1):
-    aux_lt = []
-    aux_str = ''
-    for i, c in enumerate(str1):
-        if c != ' ':
-            aux_str += c    # WE COULD HAVE USED LT HERE, MORE EFFICIENT
-        elif c == ' ':
-            aux_lt.append(aux_str)  # WE COULD HAVE USED STR BUT NOT EFFICIENT!
-            aux_str = ''
-    aux_lt.append(aux_str) # REMEMBER THAT THE LAST ONE DOEN'T HAVE SPACE!
-    aux_lt.reverse()   
-    return ' '.join(aux_lt)
-
-    
-
-if __name__ == '__main__':
-    import doctest
-    doctest.testmod()
-

src/further_examples/useful/version_info.py

@@ -1,9 +1,20 @@
-import sys 
+import sys
-print "System version:",sys.version
+print("System version:", sys.version, '\n')
-import numpy as np
-print "Numpy version:",np.version.version
-import matplotlib
-print "Matplotlib version:",matplotlib.__version__
-import pandas as pd
-print "Pandas version:",pd.__version__
 
+try:
+    import numpy
+    print("\nNumpy version:", numpy.__version__)
+except ImportError as e:
+    print(e)
+
+try:
+    import matplotlib
+    print("\nMatplotlib version:", matplotlib.__version__)
+except ImportError as e:
+    print(e)
+
+try:
+    import pandas
+    print("\nPandas version:", pandas.__version__)
+except ImportError as e:
+    print(e)