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#!/usr/bin/python3
import os
import os.path
import sqlite3
from argparse import ArgumentParser
from math import log
import utils
from myconfig import MyConfig
from dirwalk import walkIndex
config = MyConfig()
#change cwd to the word recognizer directory
words_dir = config.getWordRecognizerDir()
os.chdir(words_dir)
#chdir done
############################################################
# Create Bigram Database #
############################################################
CREATE_BIGRAM_DDL = '''
CREATE TABLE bigram (
prefix TEXT NOT NULL,
postfix TEXT NOT NULL,
freq INTEGER NOT NULL
);
'''
CREATE_BIGRAM_PREFIX_INDEX_DDL = '''
CREATE INDEX bigram_prefix_index on bigram(prefix);
'''
CREATE_BIGRAM_POSTFIX_INDEX_DDL = '''
CREATE INDEX bigram_postfix_index on bigram(postfix);
'''
SELECT_ALL_NGRAM_DML = '''
SELECT words, freq FROM ngram;
'''
INSERT_BIGRAM_DML = '''
INSERT INTO bigram(prefix, postfix, freq) VALUES (?, ?, ?);
'''
def createBigramSqlite(workdir):
print(workdir, 'create bigram')
filename = config.getBigramFileName()
filepath = workdir + os.sep + filename
print(filepath)
if os.access(filepath, os.F_OK):
os.unlink(filepath)
conn = sqlite3.connect(filepath)
cur = conn.cursor()
cur.execute(CREATE_BIGRAM_DDL)
cur.execute(CREATE_BIGRAM_PREFIX_INDEX_DDL)
cur.execute(CREATE_BIGRAM_POSTFIX_INDEX_DDL)
conn.commit()
if conn:
conn.close()
def populateBigramSqlite(workdir):
print(workdir, 'populate bigram')
sep = config.getWordSep()
filename = config.getBigramFileName()
filepath = workdir + os.sep + filename
bigram_conn = sqlite3.connect(filepath)
bigram_cur = bigram_conn.cursor()
length = 2
filename = config.getNgramFileName(length)
filepath = workdir + os.sep + filename
ngram_conn = sqlite3.connect(filepath)
ngram_cur = ngram_conn.cursor()
#begin processing
rows = ngram_cur.execute(SELECT_ALL_NGRAM_DML).fetchall()
for row in rows:
(words_str, freq) = row
words = words_str.strip(sep).split(sep, 1)
assert len(words) == length
(prefix, postfix) = words
bigram_cur.execute(INSERT_BIGRAM_DML, (prefix, postfix, freq))
#print(prefix, postfix, freq)
bigram_conn.commit()
ngram_conn.commit()
if bigram_conn:
bigram_conn.close()
if ngram_conn:
ngram_conn.close()
############################################################
# Information Entropy Model #
############################################################
def computeEntropy(freqs):
print(freqs)
totalfreq = sum(freqs)
freqs = [ freq / float(totalfreq) for freq in freqs ]
assert 1 == sum(freqs)
entropy = sum([ - freq * log(freq) for freq in freqs ])
print(entropy)
return entropy
############################################################
# Get Threshold Pass #
############################################################
############################################################
# Get Word Pass #
############################################################
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