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fixedSizeCode.py
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fixedSizeCode.py
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"functions in this file encode digits of fixed size into text; and decode them from text to digits"
import config
import utils
import bigBitField
import time
"""
encodes a single word
- bits: a bit field object with the data to encode
- bitsRange: the range to encode this from
- startWord: previous word encoded (either 1 or 2 words depending on wordsPerState)
- markovChainDict: dictionary with the chain to use to encode data
returns (word, newRange)
"""
def encodeBitsToWord(bitsField, bitsRange, startWord, markovChainDict):
# get probabilities for the start word
wordProbs = markovChainDict[utils.lowerWordOrList(startWord)][1]
# get the range covered by every word
wordRanges = utils.computeWordRanges(bitsRange, wordProbs, bitsField.totalFieldLen())
# look for the right partition for the bits
precision = len(wordRanges[0][1][0])
bits = bitsField.getFirstNBits(precision)
bestWord = filter(
lambda wr:
utils.binaryLowerEqualThan(wr[1][0], bits) and utils.binaryLowerEqualThan(bits, wr[1][1]),
wordRanges)
return bestWord[0]
"""
encodes all a bit field to a list of words, using a markov chain
- bitsField: a bit field object with the data to encode
- markovChain: chain to use to encode data
- startWord: if it is not the default, what was the previous word before this text
returns wordList
"""
def encodeBitsToWordList(bitsField, markovChain, startWord = config.startSymbol, wordsPerState = 1):
bitsField = bitsField.copy()
lastTime = time.time()
secondsForStatusPrint = 20
words = []
nextRange = ["0", "1"]
markovChainDict = utils.markovChainToDictionary(markovChain)
while True:
# encode to one word
(word, nextRange) = encodeBitsToWord(bitsField, nextRange, startWord, markovChainDict)
words.append(word)
# compute previous word (or bigram) for next iteration
if wordsPerState == 1:
startWord = word
elif wordsPerState == 2:
if word == config.startSymbol:
startWord = (config.startSymbol, config.startSymbol)
else:
startWord = (startWord[1], word)
# optimization, remove start of range when it is identical in both sides
nextRange2 = utils.removeCommonBitsInRange(nextRange)
bitsField.popFirstNBits(len(nextRange[0])-len(nextRange2[0]))
nextRange = nextRange2
if time.time()-lastTime > secondsForStatusPrint:
print " - remaining bits: " + repr(bitsField.totalFieldLen())
lastTime = time.time()
# we exit when our range describes only to our number
if bitsField.totalFieldLen() == 0 or (bitsField.totalFieldLen() == 1 and nextRange[0][0] == nextRange[1][0]):
break
return words
if __name__ == '__main__':
print "testing fixedSizeCode.py"
testMarkov = config.testMarkov
testMarkovDict = utils.markovChainToDictionary(testMarkov)
testMarkov2 = config.testMarkov2
testMarkovDict2 = utils.markovChainToDictionary(testMarkov2)
# this is "01000110 01011010 11111111"
testBitField = bigBitField.BigBitField([70, 90, 255])
print "A:"
print encodeBitsToWord(testBitField, ["0", "1"], config.startSymbol, testMarkovDict) == ('A', ('00', '01'))
print "A2:"
print encodeBitsToWord(testBitField, ["0", "1"], (config.startSymbol, config.startSymbol), testMarkovDict2) == ('A', ('00', '01'))
print "B:"
print encodeBitsToWord(testBitField, ["0", "1"], "A", testMarkovDict) == ('B', ('01', '01'))
print "B2:"
print encodeBitsToWord(testBitField, ["0", "1"], (config.startSymbol, "A"), testMarkovDict2) == ('B', ('01', '01'))
print "C:"
miniBF = bigBitField.BigBitField("0", False)
print encodeBitsToWord(miniBF, ["0", "1"], "A", testMarkovDict) == ('A', ('0', '0'))
print "C2:"
print encodeBitsToWord(miniBF, ["0", "1"], (config.startSymbol, "A"), testMarkovDict2) == ('A', ('0', '0'))
print "SIZE 1"
print "testWordList 1:"
miniBF = bigBitField.BigBitField("0", False)
print encodeBitsToWordList(miniBF, testMarkov) == ['A']
print "testWordList 1b:"
print encodeBitsToWordList(miniBF, testMarkov2, (config.startSymbol, config.startSymbol), 2) == ['A']
print "testWordList 2:"
miniBF = bigBitField.BigBitField("1", False)
print encodeBitsToWordList(miniBF, testMarkov) == ['C']
print "SIZE 2"
print "testWordList 3:"
miniBF = bigBitField.BigBitField("00", False)
print encodeBitsToWordList(miniBF, testMarkov) == ['A', 'A']
print "testWordList 4:"
miniBF = bigBitField.BigBitField("01", False)
print encodeBitsToWordList(miniBF, testMarkov) == ['A', '<START>']
print "testWordList 5:"
miniBF = bigBitField.BigBitField("10", False)
print encodeBitsToWordList(miniBF, testMarkov) == ['B']
print "testWordList 6:"
miniBF = bigBitField.BigBitField("11", False)
print encodeBitsToWordList(miniBF, testMarkov) == ['C']
print "SIZE 3"
print "testWordList 7:"
miniBF = bigBitField.BigBitField("000", False)
print encodeBitsToWordList(miniBF, testMarkov) == ['A', 'A']
print "testWordList 8:"
miniBF = bigBitField.BigBitField("001", False)
print encodeBitsToWordList(miniBF, testMarkov) == ['A', 'B']
print "testWordList 9:"
miniBF = bigBitField.BigBitField("010", False)
print encodeBitsToWordList(miniBF, testMarkov) == ['A', 'C']
print "testWordList 10:"
miniBF = bigBitField.BigBitField("011", False)
print encodeBitsToWordList(miniBF, testMarkov) == ['A', '<START>']
print "testWordList 11:"
miniBF = bigBitField.BigBitField("100", False)
print encodeBitsToWordList(miniBF, testMarkov) == ['B', 'A']
print "testWordList 12:"
miniBF = bigBitField.BigBitField("101", False)
print encodeBitsToWordList(miniBF, testMarkov) == ['B', '<START>']
print "testWordList 13:"
miniBF = bigBitField.BigBitField("110", False)
print encodeBitsToWordList(miniBF, testMarkov) == ['C', 'A']
print "testWordList 14:"
miniBF = bigBitField.BigBitField("111", False)
print encodeBitsToWordList(miniBF, testMarkov) == ['C', '<START>']
print "SIZE 4"
print "testWordList 15:"
miniBF = bigBitField.BigBitField("0000", False)
print encodeBitsToWordList(miniBF, testMarkov) == ['A', 'A', 'A']
print "testWordList 16:"
miniBF = bigBitField.BigBitField("0001", False)
print encodeBitsToWordList(miniBF, testMarkov) == ['A', 'A', '<START>']
print "testWordList 16b:"
miniBF = bigBitField.BigBitField("0001", False)
print encodeBitsToWordList(miniBF, testMarkov2, (config.startSymbol, config.startSymbol), 2) == ['A', 'A', '<START>']
print "testWordList 17:"
miniBF = bigBitField.BigBitField(
"0010101010000101010101110010101011011010101000111010101010010011101101010110101010101010001110101010", False)
print encodeBitsToWordList(miniBF, testMarkov) == ['A', 'B', 'B', 'B', 'B', 'A', 'A', 'C', 'C', 'C', 'C', '<START>', 'B', 'B', 'B', 'B', 'B', 'C', '<START>', 'A', 'C', 'C', 'C', 'A', '<START>', 'B', 'C', 'C', 'C', 'C', 'B', 'A', '<START>', 'B', '<START>', 'A', 'C', 'C', '<START>', 'A', 'C', 'C', 'C', 'C', 'C', 'C', 'A', '<START>', 'B', 'C', 'C', 'C']
print "testWordList 17b:"
print encodeBitsToWordList(miniBF, testMarkov2, (config.startSymbol, config.startSymbol), 2) == ['A', 'B', 'B', 'B', 'B', 'A', 'A', 'C', 'C', 'C', 'C', '<START>', 'B', 'B', 'B', 'B', 'B', 'C', '<START>', 'A', 'C', 'C', 'C', 'A', '<START>', 'B', 'C', 'C', 'C', 'C', 'B', 'A', '<START>', 'B', '<START>', 'A', 'C', 'C', '<START>', 'A', 'C', 'C', 'C', 'C', 'C', 'C', 'A', '<START>', 'B', 'C', 'C', 'C']
print "testWordList 18:"
miniBF = bigBitField.BigBitField(
"101011101011110101101011111010100101010100101111010111", False)
print encodeBitsToWordList(miniBF, testMarkov) == ['B', 'C', '<START>', 'B', 'C', '<START>', 'C', 'B', 'B', 'C', 'C', '<START>', 'C', 'C', 'C', 'C', 'B', 'B', 'B', 'B', 'A', 'C', '<START>', 'C', 'B', 'B', '<START>']
print "done"