116 lines
3.6 KiB
Python
Executable File
116 lines
3.6 KiB
Python
Executable File
#!/usr/bin/env python
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import sys, re, operator, string
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#
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# The all-important data stack
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#
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stack = []
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#
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# The heap. Let's make it an associative array
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# mapping names to data (i.e. variables)
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#
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heap = {}
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#
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# The new "words" of our program
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#
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def read_file():
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"""
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Takes a path to a file and returns the entire
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contents of the file as a string.
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Path to file expected to be on the stack
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"""
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f = open(stack.pop())
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# Push the result onto the stack
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stack.append([f.read()])
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f.close()
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def filter_chars():
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"""
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Takes a string and returns a copy with all nonalphanumeric
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chars replaced by white space. The data is assumed to be
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on the stack.
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"""
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# This is not in style. RE is too high-level, but using it
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# for doing this fast and short. Push the pattern onto stack
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stack.append(re.compile('[\W_]+'))
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# Push the result onto the stack
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stack.append([stack.pop().sub(' ', stack.pop()[0]).lower()])
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def scan():
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"""
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Takes a string and scans for words, returning
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a list of words. The data is assumed to be on the stack.
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"""
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# Push the result onto the stack.
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# Again, split() is too high-level for this style, but using it
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# for doing this fast and short. Left as exercise.
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stack.append(stack.pop()[0].split())
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def remove_stop_words():
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"""
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Takes a list of words and returns a copy with all stop
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words removed. The data is assumed to be on the stack.
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"""
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f = open('../stop_words.txt')
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stack.append(f.read().split(','))
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f.close()
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# add single-letter words
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stack[1].extend(list(string.ascii_lowercase))
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heap['stop_words'] = stack.pop()
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# Again, this is too high-level for this style, but using it
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# for doing this fast and short. Left as exercise.
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stack.append([w for w in stack.pop() if not w in heap['stop_words']])
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def frequencies():
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"""
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Takes a list of words and returns a dictionary associating
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words with frequencies of occurrence. The word list is assumed
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to be on the stack.
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"""
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heap['word_list'] = stack.pop()
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heap['word_freqs'] = {}
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# A little flavour of the real Forth style here...
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for wi in range(0, len(heap['word_list'])):
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stack.append(heap['word_list'][wi]) # Push the word, stack[0]
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# ... but the following line is not in style, because the naive implementation
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# would be too slow, or we'd need to implement faster, hash-based search
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if stack[0] in heap['word_freqs']:
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stack.append((heap['word_freqs'][stack[0]], heap['word_freqs'][stack[0]])) # (w, f) in stack[1]
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stack[1] = (stack[0], stack[1][1] + 1) # Swap the tuple the stack with a new one
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heap['word_freqs'][stack[-1][0]] = stack[-1][1] # Load the updated freq back onto the heap
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else:
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stack.append((stack[0], 1)) # Push the tuple (w, 1)
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heap['word_freqs'][stack[-1][0]] = stack[-1][1] # Load it back to the heap
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stack.pop() # Pop (w, f)
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stack.pop() # Pop word
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# Push the result onto the stack
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stack.append(heap['word_freqs'])
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def sort():
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"""
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Takes a dictionary of words and their frequencies
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and returns a list of pairs where the entries are
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sorted by frequency
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"""
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# Not in style, left as exercise
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stack.append(sorted(stack.pop().iteritems(), key=operator.itemgetter(1), reverse=True))
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#
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# The main function
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#
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stack.append(sys.argv[1])
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read_file(); filter_chars(); scan(); remove_stop_words()
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frequencies(); sort()
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word_freqs = stack.pop()
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for i in range(0, 25):
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stack.append(word_freqs[i])
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print stack[0][0], ' - ', stack[0][1]
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stack.pop()
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