spaCy/spacy/lang/nl/lemmatizer.py
Paul O'Leary McCann fd759a881b
Fix inconsistent lemmas (#9405)
* Add util function to unique lists and preserve order

* Use unique function instead of list(set())

list(set()) has the issue that it's not consistent between runs of the
Python interpreter, so order can vary.

list(set()) calls were left in a few places where they were behind calls
to sorted(). I think in this case the calls to list() can be removed,
but this commit doesn't do that.

* Use the existing pattern for this
2021-10-11 11:38:45 +02:00

123 lines
4.5 KiB
Python

from typing import List, Tuple
from ...pipeline import Lemmatizer
from ...tokens import Token
class DutchLemmatizer(Lemmatizer):
@classmethod
def get_lookups_config(cls, mode: str) -> Tuple[List[str], List[str]]:
if mode == "rule":
required = ["lemma_lookup", "lemma_rules", "lemma_exc", "lemma_index"]
return (required, [])
else:
return super().get_lookups_config(mode)
def lookup_lemmatize(self, token: Token) -> List[str]:
"""Overrides parent method so that a lowercased version of the string
is used to search the lookup table. This is necessary because our
lookup table consists entirely of lowercase keys."""
lookup_table = self.lookups.get_table("lemma_lookup", {})
string = token.text.lower()
return [lookup_table.get(string, string)]
# Note: CGN does not distinguish AUX verbs, so we treat AUX as VERB.
def rule_lemmatize(self, token: Token) -> List[str]:
# Difference 1: self.rules is assumed to be non-None, so no
# 'is None' check required.
# String lowercased from the get-go. All lemmatization results in
# lowercased strings. For most applications, this shouldn't pose
# any problems, and it keeps the exceptions indexes small. If this
# creates problems for proper nouns, we can introduce a check for
# univ_pos == "PROPN".
cache_key = (token.lower, token.pos)
if cache_key in self.cache:
return self.cache[cache_key]
string = token.text
univ_pos = token.pos_.lower()
if univ_pos in ("", "eol", "space"):
forms = [string.lower()]
self.cache[cache_key] = forms
return forms
index_table = self.lookups.get_table("lemma_index", {})
exc_table = self.lookups.get_table("lemma_exc", {})
rules_table = self.lookups.get_table("lemma_rules", {})
index = index_table.get(univ_pos, {})
exceptions = exc_table.get(univ_pos, {})
rules = rules_table.get(univ_pos, {})
string = string.lower()
if univ_pos not in (
"noun",
"verb",
"aux",
"adj",
"adv",
"pron",
"det",
"adp",
"num",
):
forms = [string]
self.cache[cache_key] = forms
return forms
lemma_index = index_table.get(univ_pos, {})
# string is already lemma
if string in lemma_index:
forms = [string]
self.cache[cache_key] = forms
return forms
exc_table = self.lookups.get_table("lemma_exc", {})
exceptions = exc_table.get(univ_pos, {})
# string is irregular token contained in exceptions index.
try:
forms = [exceptions[string][0]]
self.cache[cache_key] = forms
return forms
except KeyError:
pass
# string corresponds to key in lookup table
lookup_table = self.lookups.get_table("lemma_lookup", {})
looked_up_lemma = lookup_table.get(string)
if looked_up_lemma and looked_up_lemma in lemma_index:
forms = [looked_up_lemma]
self.cache[cache_key] = forms
return forms
rules_table = self.lookups.get_table("lemma_rules", {})
oov_forms = []
for old, new in rules:
if string.endswith(old):
form = string[: len(string) - len(old)] + new
if not form:
pass
elif form in index:
forms = [form]
self.cache[cache_key] = forms
return forms
else:
oov_forms.append(form)
forms = list(dict.fromkeys(oov_forms))
# Back-off through remaining return value candidates.
if forms:
for form in forms:
if form in exceptions:
forms = [form]
self.cache[cache_key] = forms
return forms
if looked_up_lemma:
forms = [looked_up_lemma]
self.cache[cache_key] = forms
return forms
else:
self.cache[cache_key] = forms
return forms
elif looked_up_lemma:
forms = [looked_up_lemma]
self.cache[cache_key] = forms
return forms
else:
forms = [string]
self.cache[cache_key] = forms
return forms