Source code for tryalgo.predictive_text

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""\
Predictive text for mobile phones
jill-jenn vie et christoph durr and louis abraham - 2014-2019
"""

__all__ = ["predictive_text", "propose"]

# snip{
t9 = "22233344455566677778889999"
#     abcdefghijklmnopqrstuvwxyz   mapping on the phone


def letter_to_digit(x):
    """:returns: the digit correspondence for letter x"""
    assert 'a' <= x <= 'z'
    return t9[ord(x) - ord('a')]


def code_word(word):
    """:returns: the digit correspondence for given word"""
    return ''.join(map(letter_to_digit, word))


[docs]def predictive_text(dic): """Predictive text for mobile phones :param dic: associates weights to words from [a-z]* :returns: a dictionary associating to words from [2-9]* a corresponding word from the dictionary with highest weight :complexity: linear in total word length """ # total_weight[p] = total weight of words having prefix p total_weight = {} for word, weight in dic: prefix = "" for x in word: prefix += x if prefix in total_weight: total_weight[prefix] += weight else: total_weight[prefix] = weight # prop[s] = prefix to display for s prop = {} for prefix in total_weight: code = code_word(prefix) if (code not in prop or total_weight[prop[code]] < total_weight[prefix]): prop[code] = prefix return prop
[docs]def propose(prop, seq): """wrapper to access a dictionary even for non-present keys""" if seq in prop: return prop[seq] return None
# snip}