127 lines
4.3 KiB
Python
Executable File
127 lines
4.3 KiB
Python
Executable File
#!/usr/bin/env python
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import sys, os, string
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# Utility for handling the intermediate 'secondary memory'
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def touchopen(filename, *args, **kwargs):
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try:
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os.remove(filename)
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except OSError:
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pass
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open(filename, "a").close() # "touch" file
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return open(filename, *args, **kwargs)
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# The constrained memory, which consists of only 1024 bytes by constraint
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data = []
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# Overall strategy:
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# - read the input file one line at a time
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# - filter the characters, normalize to lower case
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# - identify words, incrementing corresponding counts (in secondary memory)
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# We're lucky:
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# The stop words are only 556 bytes and the lines are all less than
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# 80 characters, so we can use that knowledge to simplify the problem:
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# we can have the stop words loaded in memory while processing one line
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# of the input at a time.
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# If these two assumptions didn't hold, the algorithm would need to be
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# changed considerably.
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# Load the list of stop words
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f = open('../stop_words.txt')
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data = [f.read(1024).split(',')] # data[0] holds the stop words
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f.close()
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data.append([]) # data[1] is the line
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data.append(None) # data[2] is the index of the start_char of a word
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data.append(0) # data[3] is an index, i = 0
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data.append(False) # data[4] is a flag indicating where a word was found
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data.append('') # data[5] is the word
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data.append('') # data[6] is word,NNNN from the word_freqs file, and then just the word
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data.append(0) # data[7] is frequency
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word_freqs = touchopen('word_freqs', 'r+')
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f = open(sys.argv[1])
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while True:
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data[1] = [f.readline()]
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#print data[1]
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if data[1] == ['']: # end of input file
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break
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data[2] = None
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data[3] = 0
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for c in data[1][0]: # elimination of symbol c left as exercise
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if data[2] == None:
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if c.isalnum():
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# We found the start of a word
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data[2] = data[3]
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else:
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if not c.isalnum():
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# We found the end of a word. Process it
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data[4] = False
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data[5] = data[1][0][data[2]:data[3]].lower()
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#print "Looking at " + data[5]
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# Ignore words with less than 2 characters and stop words
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if len(data[5]) >= 2 and data[5] not in data[0]:
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# Let's see if it already exists
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while True:
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data[6] = word_freqs.readline().strip()
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#print " Comparing to " + data[6]
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if data[6] == '':
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break;
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data[7] = int(data[6].split(',')[1])
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data[6] = data[6].split(',')[0].strip() # word, no white space
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if data[5] == data[6]:
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data[7] += 1
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data[4] = True
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break
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if not data[4]:
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word_freqs.writelines("%20s,%04d\n" % (data[5], 1))
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if data[5] == 'i, n':
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print "Got it " + str(data[1])
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else:
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word_freqs.seek(-26, 1)
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word_freqs.writelines("%20s,%04d\n" % (data[5], data[7]))
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word_freqs.seek(0,0)
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# Let's reset
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data[2] = None
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data[3] += 1
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f.close()
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word_freqs.flush()
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# Now we need to find the 25 most frequently occuring words.
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# We don't need anything from the previous values in memory
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del data[:]
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# Let's use the first 25 entries for the top 25 words
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data = data + [[]]*(25 - len(data))
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data.append('') # data[25] is word,freq read from word_freqs file, and then word
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data.append(0) # data[26] is freq
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#print data
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while True:
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data[25] = word_freqs.readline().strip()
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if data[25] == '':
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break;
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data[26] = int(data[25].split(',')[1])
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data[25] = data[25].split(',')[0].strip() # word, no white space
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for i in range(25): # elimination of symbol i left as exercise
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if data[i] == [] or data[i][1] < data[26]:
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#print str(i) + " " + str(data[25]) + " " + str(data[26])
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data.insert(i, [data[25], data[26]])
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del data[26] # pop the last element
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break
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for tf in data[0:25]: # elimination of symbol tf left as exercise
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if len(tf) == 2:
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print tf[0], ' - ', tf[1]
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word_freqs.close()
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