88 lines
2.9 KiB
Python
88 lines
2.9 KiB
Python
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from typing import List, Tuple
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from ...pipeline import Lemmatizer
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from ...tokens import Token
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class FrenchLemmatizer(Lemmatizer):
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"""
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French language lemmatizer applies the default rule based lemmatization
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procedure with some modifications for better French language support.
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The parts of speech 'ADV', 'PRON', 'DET', 'ADP' and 'AUX' are added to use
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the rule-based lemmatization. As a last resort, the lemmatizer checks in
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the lookup table.
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"""
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@classmethod
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def get_lookups_config(cls, mode: str) -> Tuple[List[str], List[str]]:
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if mode == "rule":
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required = ["lemma_lookup", "lemma_rules", "lemma_exc", "lemma_index"]
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return (required, [])
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else:
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return super().get_lookups_config(mode)
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def rule_lemmatize(self, token: Token) -> List[str]:
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cache_key = (token.orth, token.pos)
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if cache_key in self.cache:
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return self.cache[cache_key]
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string = token.text
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univ_pos = token.pos_.lower()
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if univ_pos in ("", "eol", "space"):
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return [string.lower()]
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elif "lemma_rules" not in self.lookups or univ_pos not in (
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"noun",
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"verb",
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"adj",
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"adp",
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"adv",
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"aux",
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"cconj",
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"det",
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"pron",
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"punct",
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"sconj",
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):
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return self.lookup_lemmatize(token)
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index_table = self.lookups.get_table("lemma_index", {})
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exc_table = self.lookups.get_table("lemma_exc", {})
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rules_table = self.lookups.get_table("lemma_rules", {})
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lookup_table = self.lookups.get_table("lemma_lookup", {})
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index = index_table.get(univ_pos, {})
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exceptions = exc_table.get(univ_pos, {})
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rules = rules_table.get(univ_pos, [])
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string = string.lower()
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forms = []
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# first try lookup in table based on upos
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if string in index:
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forms.append(string)
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self.cache[cache_key] = forms
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return forms
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# then add anything in the exceptions table
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forms.extend(exceptions.get(string, []))
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# if nothing found yet, use the rules
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oov_forms = []
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if not forms:
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for old, new in rules:
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if string.endswith(old):
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form = string[: len(string) - len(old)] + new
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if not form:
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pass
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elif form in index or not form.isalpha():
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forms.append(form)
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else:
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oov_forms.append(form)
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# if still nothing, add the oov forms from rules
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if not forms:
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forms.extend(oov_forms)
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# use lookups, which fall back to the token itself
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if not forms:
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forms.append(lookup_table.get(string, [string])[0])
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forms = list(dict.fromkeys(forms))
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self.cache[cache_key] = forms
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return forms
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