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#!/usr/bin/env python
import sys, re, operator, string
# The all-important data stack
stack = []
# The heap. Maps names to data (i.e. variables)
heap = {}
# The new "words" (procedures) of our program
def read_file():
Takes a path to a file on the stack and places the entire
contents of the file back on the stack.
f = open(stack.pop())
# Push the result onto the stack
def filter_chars():
Takes data on the stack and places back a copy with all
nonalphanumeric chars replaced by white space.
# This is not in style. RE is too high-level, but using it
# for doing this fast and short. Push the pattern onto stack
# Push the result onto the stack
stack.append([stack.pop().sub(' ', stack.pop()[0]).lower()])
def scan():
Takes a string on the stack and scans for words, placing
the list of words back on the stack
# Again, split() is too high-level for this style, but using
# it for doing this fast and short. Left as exercise.
def remove_stop_words():
Takes a list of words on the stack and removes stop words.
f = open('../stop_words.txt')
# add single-letter words
heap['stop_words'] = stack.pop()
# Again, this is too high-level for this style, but using it
# for doing this fast and short. Left as exercise.
heap['words'] = []
while len(stack) > 0:
if stack[-1] in heap['stop_words']:
stack.pop() # pop it and drop it
heap['words'].append(stack.pop()) # pop it, store it
stack.extend(heap['words']) # Load the words onto the stack
del heap['stop_words']; del heap['words'] # Not needed
def frequencies():
Takes a list of words and returns a dictionary associating
words with frequencies of occurrence.
heap['word_freqs'] = {}
# A little flavour of the real Forth style here...
while len(stack) > 0:
# ... but the following line is not in style, because the
# naive implementation would be too slow
if stack[-1] in heap['word_freqs']:
# Increment the frequency, postfix style: f 1 +
stack.append(heap['word_freqs'][stack[-1]]) # push f
stack.append(1) # push 1
stack.append(stack.pop() + stack.pop()) # add
stack.append(1) # Push 1 in stack[2]
# Load the updated freq back onto the heap
heap['word_freqs'][stack.pop()] = stack.pop()
# Push the result onto the stack
del heap['word_freqs'] # We don't need this variable anymore
def sort():
# Not in style, left as exercise
stack.extend(sorted(stack.pop().items(), key=operator.itemgetter(1)))
# The main function
read_file(); filter_chars(); scan(); remove_stop_words()
frequencies(); sort()
# Check stack length against 1, because after we process
# the last word there will be one item left
while stack[-1] < 25 and len(stack) > 1:
heap['i'] = stack.pop()
(w, f) = stack.pop(); print(w, ' - ', f)
stack.append(heap['i']); stack.append(1)
stack.append(stack.pop() + stack.pop())
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