python統計文本字符串里面單詞出現的頻率

# word frequency in a text

tested with Python24    vegaseat    25aug2005
Chinese wisdom ...
str1 = """Man who run in front of car, get tired.
Man who run behind car, get exhausted."""
print "Original string:"
print str1
print
create a list of words separated at whitespaces
wordList1 = str1.split(None)
strip any punctuation marks and build modified word list
start with an empty list
wordList2 = []
for word1 in wordList1:

# last character of each word
lastchar = word1[-1:]
# use a list of punctuation marks
if lastchar in [",", ".", "!", "?", ";"]:
    word2 = word1.rstrip(lastchar)
else:
    word2 = word1
# build a wordList of lower case modified words
wordList2.append(word2.lower())


print "Word list created from modified string:"
print wordList2
print
create a wordfrequency dictionary
start with an empty dictionary
freqD2 = {}
for word2 in wordList2:
    freqD2[word2] = freqD2.get(word2, 0) + 1
create a list of keys and sort the list
all words are lower case already
keyList = freqD2.keys()
keyList.sort()
print "Frequency of each word in the word list (sorted):"
for key2 in keyList:
  print "%-10s %d" % (key2, freqD2[key2])</pre>