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https://github.com/osm-search/Nominatim.git
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109 lines
3.6 KiB
Python
109 lines
3.6 KiB
Python
# SPDX-License-Identifier: GPL-2.0-only
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#
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# This file is part of Nominatim. (https://nominatim.org)
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#
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# Copyright (C) 2022 by the Nominatim developer community.
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# For a full list of authors see the git log.
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"""
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Generic processor for names that creates abbreviation variants.
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"""
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import itertools
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import datrie
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from nominatim.tokenizer.token_analysis.config_variants import get_variant_config
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### Configuration section
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def configure(rules, normalization_rules):
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""" Extract and preprocess the configuration for this module.
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"""
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config = {}
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config['replacements'], config['chars'] = get_variant_config(rules.get('variants'),
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normalization_rules)
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config['variant_only'] = rules.get('mode', '') == 'variant-only'
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return config
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### Analysis section
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def create(transliterator, config):
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""" Create a new token analysis instance for this module.
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"""
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return GenericTokenAnalysis(transliterator, config)
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class GenericTokenAnalysis:
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""" Collects the different transformation rules for normalisation of names
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and provides the functions to apply the transformations.
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"""
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def __init__(self, to_ascii, config):
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self.to_ascii = to_ascii
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self.variant_only = config['variant_only']
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# Set up datrie
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if config['replacements']:
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self.replacements = datrie.Trie(config['chars'])
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for src, repllist in config['replacements']:
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self.replacements[src] = repllist
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else:
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self.replacements = None
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def get_variants_ascii(self, norm_name):
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""" Compute the spelling variants for the given normalized name
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and transliterate the result.
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"""
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results = set()
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for variant in self._generate_word_variants(norm_name):
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if not self.variant_only or variant.strip() != norm_name:
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trans_name = self.to_ascii.transliterate(variant).strip()
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if trans_name:
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results.add(trans_name)
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return list(results)
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def _generate_word_variants(self, norm_name):
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baseform = '^ ' + norm_name + ' ^'
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baselen = len(baseform)
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partials = ['']
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startpos = 0
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if self.replacements is not None:
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pos = 0
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force_space = False
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while pos < baselen:
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full, repl = self.replacements.longest_prefix_item(baseform[pos:],
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(None, None))
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if full is not None:
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done = baseform[startpos:pos]
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partials = [v + done + r
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for v, r in itertools.product(partials, repl)
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if not force_space or r.startswith(' ')]
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if len(partials) > 128:
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# If too many variants are produced, they are unlikely
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# to be helpful. Only use the original term.
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startpos = 0
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break
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startpos = pos + len(full)
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if full[-1] == ' ':
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startpos -= 1
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force_space = True
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pos = startpos
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else:
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pos += 1
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force_space = False
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# No variants detected? Fast return.
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if startpos == 0:
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return (norm_name, )
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if startpos < baselen:
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return (part[1:] + baseform[startpos:-1] for part in partials)
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return (part[1:-1] for part in partials)
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