Move to a chaining model for tokenization.

This model also explores more tokenization possibilities.
With this, the tokenization tests are passed.
This commit is contained in:
kenkeiras 2018-04-15 20:06:21 +02:00
parent 998a183fd2
commit 79034f85a9
3 changed files with 153 additions and 97 deletions

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@ -8,6 +8,15 @@ from collections import namedtuple
Atom = namedtuple('Atom', field_names='name')
def is_atom(element, name=None):
'''Check if an element is an atom with a specific name.'''
if not isinstance(element, Atom):
return False
if name is None:
return True
return element.name == name
def a(name):
'''Build an atom with a given name.'''

View File

@ -7,25 +7,69 @@ from .atoms import Atom
from . import parsing
from . import knowledge_evaluation
from .modifiable_property import is_modifiable_property
import random
def diff_knowledge(before, after):
import jsondiff
return jsondiff.diff(before, after)
def randomized_weighted_list(elements):
# Randomized
randomized = list(elements)
random.shuffle(randomized)
# And return only once
already_returned = set()
for e in randomized:
if e in already_returned:
continue
yield e
already_returned.add(e)
class KnowledgeBase(object):
def __init__(self, knowledge={}, examples=[], trained=[]):
self.knowledge = copy.copy(knowledge)
self.originals = []
self.examples = copy.copy(examples)
self.trained = copy.copy(trained)
self.tokenization = set()
self.structural_elements = set()
self.token_chains = {}
self.tokens = set()
def add_token_pair(self, precedent, consequent):
self.add_token(precedent)
self.add_token(consequent)
if precedent not in self.token_chains:
self.token_chains[precedent] = []
self.token_chains[precedent].append(consequent)
def add_token(self, token):
self.tokens.add(token)
if (not isinstance(token, Atom)) and (token not in self.structural_elements):
session().annotate('Found new structural element “{}'.format(token))
self.structural_elements.add(token)
def expected_token_after_precedent(self, precedent=None):
if precedent not in self.token_chains: # If there's no known precedent, just return all tokens
return randomized_weighted_list(self.tokens)
return randomized_weighted_list(self.token_chains[precedent])
def train_tokenizer(self, example):
with session().log('Train'):
parsing.integrate_tokenization(self, example)
with session().log('Training tokenizer'):
session().annotate("Example: {}".format(example))
tokens = parsing.integrate_tokenization(self, example)
# Integrate knowledge of concept
for token in tokens:
if not token in self.knowledge:
self.knowledge[token] = {}
def train(self, examples):
knowledge_before = copy.deepcopy(self.knowledge)
@ -80,14 +124,6 @@ class KnowledgeBase(object):
return chosen
return options
def add_tokenization(self, tokenization):
with session().log('Added tokenization: “{}'.format(tokenization)):
self.tokenization.add(tokenization)
for e in tokenization:
if (not isinstance(e, Atom)) and (e not in self.structural_elements):
session().annotate('Found new structural element “{}'.format(e))
self.structural_elements.add(e)
def process(self, row):
knowledge_before = copy.deepcopy(self.knowledge)
with session().log("Process: {}".format(row)):

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@ -11,7 +11,7 @@ from functools import reduce
from typing import List, Dict
from .modifiable_property import ModifiableProperty
from . import parameters
from .atoms import Atom, a
from .atoms import Atom, a, is_atom
def lookahead_for_tokens_or_strucutral_elements(knowledge_base, remaining):
for se in knowledge_base.structural_elements:
@ -36,79 +36,84 @@ def lookahead_for_tokens_or_strucutral_elements(knowledge_base, remaining):
def to_tokens(knowledge_base, text, acc=None):
# TODO This is an extra-naïve implementation
found = 0
def to_tokens(knowledge_base, text, precedent=None):
if len(text) == 0:
session().annotate("No text remaining")
yield ['']
return
for tokenization in knowledge_base.tokenization:
with session().log("Tokenization {}".format(tokenization)):
remaining = text
possibility = []
with session().log("Tokenizing {}".format(text)):
for option in knowledge_base.expected_token_after_precedent(precedent):
with session().log("Next: “{}".format(option)):
with session().log("Matching “{}” on “{}".format(option, text)):
for token_match in tokenization_match(option, text, knowledge_base):
if token_match is None:
session().annotate("No match")
# Apply tokenization to all elmenets
for i, token in enumerate(tokenization):
with session().log("T “{}” over “{}".format(token, remaining)):
if token == Atom('token'):
for thing in knowledge_base.knowledge.keys():
session().annotate("Testing with “{}".format(thing))
if remaining.startswith(thing):
# TODO We should also branch here, probably :\
remaining = remaining[len(thing):]
possibility.append(thing)
else:
if i + 1 >= len(tokenization): # Last element, lookahead for tokens/structural elements
with session().log("Token not found, looking ahead for splits on “{}".format(remaining)):
# If we start with remaining[0:] it's not a real lookahead
# ... and it can get us trapped on infinite recursion
splits = lookahead_for_tokens_or_strucutral_elements(knowledge_base, remaining[1:])
match, remaining = token_match
if len(remaining) == len(text):
raise Exception('No text consumed in match')
if splits is None:
session().log("No splits found, keeping remaining as token “{}".format(remaining))
session().annotate('Match: “{}'.format(match))
with session().log('Remaining “{}'.format(remaining)):
for sublevel in to_tokens(knowledge_base, remaining, match):
candidate = list(filter(lambda x: x != '', [match] + sublevel))
session().annotate('Yielding candidate “{}'.format(candidate))
yield candidate
possibility.append(remaining)
remaining = ""
else:
# Consider we only have one possibility
assert len(splits) == 1
before_split, pivot, after_split = splits[0]
before_split = remaining[0] + before_split
session().log("1 split found, cutting on token “{}”, keeping “{}".format(found, before_split))
possibility.append(before_split)
remaining = pivot + after_split
else: # Not las element, use the next one as cutter
# Try with (HYPERSIMPLISTIC!) backtracking
# Cut using the next token we should use more!!!
next_token = tokenization[i + 1]
session().annotate("Trying to cut for next token on “{}".format(next_token))
cutoff = remaining.find(next_token)
if cutoff < 0:
break
possibility.append(remaining[:cutoff])
remaining = remaining[cutoff:]
else:
if remaining.find(token) < 0: # Not inmediately after!
break
remaining = remaining[len(token):]
session().annotate("OK, remaining: “{}” with {} items".format(remaining, len(tokenization) - (i + 1)))
def tokenization_match(element, text, knowledge_base):
# Constant/structural string matching
if isinstance(element, str):
if text.find(element) == 0:
# This match comes from a structuring element
# It doesn't appear on the tokenization
# So we should return it as an empty string
yield ('', text[len(element):])
return
else:
# Tokenization applicable
found += 1
if remaining == '':
session().log("Concluded possibility “{}".format(possibility))
yield possibility
else:
with session().log("Continuing with “{}".format(remaining)):
for consecuent in to_tokens(knowledge_base, remaining, possibility):
yield list(filter(lambda x: x != '', possibility + consecuent))
if found == 0:
raise Exception('No tokenization found')
# No match found
return
elif is_atom(element, 'token'):
yield from match_single_token(text, knowledge_base)
return
raise NotImplementedError()
def match_single_token(text, knowledge_base):
found_token = False
for token in knowledge_base.knowledge.keys():
if text.find(token) == 0:
yield token, text[len(token):]
found_token = True
if found_token:
return
session().annotate('No token found at the start of ”{}'.format(text))
session().annotate('using structural elements to infer it')
# TODO: review this when multiple structural elements are available
for se in knowledge_base.structural_elements:
session().annotate('Looking for se “{}” in “{}'.format(se, text))
position = text.find(se, 0)
found = position > 0 # 0 is not considered a valid position for this kind of split
if found:
session().annotate('Found ”{}”, inferring “{}'.format(se, text[:position]))
yield text[:position], text[position:]
session().annotate('No structural element or token found, inferring only token remaining')
yield text, ''
# Using other tokens for cutoff
for token in knowledge_base.knowledge.keys():
session().annotate('Looking for token “{}” in “{}'.format(token, text))
position = text.find(token)
found = position >= 0
if found:
session().annotate('Found ”{}”, in position ”{}'.format(token, position))
yield text[:position], text[position:]
def integrate_tokenization(knowledge_base, example):
text = example['text']
@ -131,7 +136,7 @@ def integrate_token_to_text_matching(knowledge_base, text, tokens):
if token in text:
before, after = text.split(token, maxsplit=1)
texts = (texts[:i] + [before]
+ [token_id]
+ [a('token')]
+ [after] + texts[i + 1:])
break
else:
@ -139,18 +144,16 @@ def integrate_token_to_text_matching(knowledge_base, text, tokens):
# Remove leftovers from splits
texts = list(filter(lambda x: x != '', texts))
session().log("Tokenized as {} over {}".format(texts, tokens))
for token_id, _token in enumerate(tokens):
# Find all elements between current token and next token
i = texts.index(token_id)
elements = [a('token')]
for i, element in enumerate(texts[:-1]):
learn_token_pair(element, texts[i + 1], knowledge_base)
i += 1
while i < len(texts) and not isinstance(texts[i], int):
elements.append(texts[i])
i += 1
return tokens
def learn_token_pair(precedent, consequent, knowledge_base):
knowledge_base.add_token_pair(precedent, consequent)
knowledge_base.add_tokenization(tuple(elements))
def pick_one_tokenization(options, knowledge_base):
'''
@ -158,26 +161,34 @@ def pick_one_tokenization(options, knowledge_base):
Just pick the one with more results.
'''
options = list(options)
with session().log("Picking among: {} options\n{}".format(len(options), '\n'.join(map(str, options)))):
return pick_by_score(options,
[
# First by number of splits
lambda tokenization: len(tokenization),
# Among them, by number of splits without structuring elements
# By number of splits without structuring elements
lambda tokenization: sum(map(
lambda split: -sum(map(
lambda split: sum(map(
lambda se: se in split, knowledge_base.structural_elements
)), tokenization))
)), tokenization)),
# By number of unknown tokens
lambda tokenization: len(list(filter(lambda token:
(token not in knowledge_base.knowledge.keys()) and
(token not in knowledge_base.structural_elements),
tokenization))),
# By number of splits
lambda tokenization: -len(tokenization),
])
def pick_by_score(options, heuristics):
for heuristic in heuristics:
assert(len(options) > 0)
options = list(map(lambda opt: (heuristic(opt), opt), options))
sorted_options = sorted(options, key=lambda x: x[0], reverse=True)
sorted_options = sorted(options, key=lambda x: x[0], reverse=False)
heuristic_cutoff = sorted_options[0][0]
session().annotate(sorted_options)
pass_heuristic = [opt for (score, opt) in sorted_options if score <= heuristic_cutoff]
options = pass_heuristic