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pull request #5

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2 changes: 1 addition & 1 deletion exercises-hello/hello.py
Original file line number Diff line number Diff line change
Expand Up @@ -8,4 +8,4 @@
# Run ./test.sh to make sure your program matches our expected output.
#
# TODO: write your code below

print "hello world"
2 changes: 2 additions & 0 deletions exercises-hello/script.py
Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
#!/usr/bin/env python
print "this is a python script!"
58 changes: 46 additions & 12 deletions exercises-more/exercises.py
Original file line number Diff line number Diff line change
Expand Up @@ -2,73 +2,107 @@
# Return the number of words in the string s. Words are separated by spaces.
# e.g. num_words("abc def") == 2
def num_words(s):
return 0
return len(s.split())

# PROB 2
# Return the sum of all the numbers in lst. If lst is empty, return 0.
def sum_list(lst):
return 0
sum = 0
for elt in lst:
sum += elt
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careful with indentation

also, use the builtin sum function!

return sum

# PROB 3
# Return True if x is in lst, otherwise return False.
def appears_in_list(x, lst):
return False
return x in lst

# PROB 4
# Return the number of unique strings in lst.
# e.g. num_unique(["a", "b", "a", "c", "a"]) == 3
def num_unique(lst):
return 0
seen = set([])
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you can just call set(lst) to transform a list into a set!

for elt in lst:
seen.add(elt)
return len(seen)

# PROB 5
# Return a new list, where the contents of the new list are lst in reverse order.
# e.g. reverse_list([3, 2, 1]) == [1, 2, 3]
def reverse_list(lst):
return []
return lst[::-1]
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there is also a builtin reversed(lst), or you can call lst.reverse()


# PROB 6
# Return a new list containing the elements of lst in sorted decreasing order.
# e.g. sort_reverse([5, 7, 6, 8]) == [8, 7, 6, 5]
def sort_reverse(lst):
return []
return sorted(lst, key=lambda num : -1 * num)
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can also call sorted(lst, reverse=True)


# PROB 7
# Return a new string containing the same contents of s, but with all the
# vowels (upper and lower case) removed. Vowels do not include 'y'
# e.g. remove_vowels("abcdeABCDE") == "bcdBCD"
def remove_vowels(s):
return s
outstr = ''
for character in s:
if not(character.lower() in ['a','e','i','o','u']):
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or simply:

for character in 'aeiouAEIOU':
    ...

outstr += character
return outstr

# PROB 8
# Return the longest word in the lst. If the lst is empty, return None.
# e.g. longest_word(["a", "aaaaaa", "aaa", "aaaa"]) == "aaaaaa"
def longest_word(lst):
return None
if not lst:
return None
else:
newlst = sorted(lst, key=lambda word : len(word))
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can just do key=len

return newlst[-1]

# PROB 9
# Return a dictionary, mapping each word to the number of times the word
# appears in lst.
# e.g. word_frequency(["a", "a", "aaa", "b", "b", "b"]) == {"a": 2, "aaa": 1, "b": 3}
def word_frequency(lst):
return {}
dict = {}
for word in lst:
if word in dict:
dict[word]=dict[word]+1
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FYI python has a += operator

else:
dict[word]=1
return dict

# PROB 10
# Return the tuple (word, count) for the word that appears the most frequently
# in the list, and the number of times the word appears. If the list is empty, return None.
# e.g. most_frequent_word(["a", "a", "aaa", "b", "b", "b"]) == ("b", 3)
def most_frequent_word(lst):
return None
if not lst:
return None
else:
dict = word_frequency(lst)
keys = dict.keys()
sortedkeys = sorted(keys, key=lambda word : dict[word])
return (sortedkeys[-1], dict[sortedkeys[-1]])

# PROB 11
# Compares the two lists and finds all the positions that are mismatched in the list.
# Assume that len(lst1) == len(lst2). Return a list containing the indices of all the
# mismatched positions in the list.
# e.g. find_mismatch(["a", "b", "c", "d", "e"], ["f", "b", "c", "g", "e"]) == [0, 3]
def find_mismatch(lst1, lst2):
return []
mismatches = []
for pos in range(len(lst1)):
if (lst1[pos]!=lst2[pos]):
mismatches.append(pos)
return mismatches

# PROB 12
# Returns the list of words that are in word_list but not in vocab_list.
def spell_checker(vocab_list, word_list):
return []
returnme = []
for word in word_list:
if not(word in vocab_list):
returnme.append(word)
return returnme

12 changes: 8 additions & 4 deletions exercises-spellchecker/dictionary.py
Original file line number Diff line number Diff line change
Expand Up @@ -16,22 +16,26 @@ def load(dictionary_name):
Each line in the file contains exactly one word.
"""
# TODO: remove the pass line and write your own code
pass
lines = set([line.strip() for line in open(dictionary_name)])
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nice!

python also has set comprehensions:

return {line.strip() for line in open(dictionary_name)}

return lines

def check(dictionary, word):
"""
Returns True if `word` is in the English `dictionary`.
"""
pass
if word in dictionary:
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just: return word in dictionary

return True
else:
return False

def size(dictionary):
"""
Returns the number of words in the English `dictionary`.
"""
pass
return len(dictionary)

def unload(dictionary):
"""
Removes everything from the English `dictionary`.
"""
pass
dictionary=set([])
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dictionary.clear()