NLTK: lemmatizer and pos_tag [duplicate]

Question

This question already has an answer here:

• wordnet lemmatization and pos tagging in python 7 answers

I build a Plaintext-Corpus and the next step is to lemmatize all my texts. I'm using the WordNetLemmatizer and need the pos_tag for each token in order to do not get the Problem that e.g. loving -> lemma = loving and love -> lemma = love...

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The default WordNetLemmatizer-POS-Tag is n (=Noun) i think, but how can i use the pos_tag? I think the expected WordNetLemmatizer-POS-Tag are diffrent to the pos_tag i get. Is there a function or something that can help me?!?!

in this line i think the word_pos is wrong and that's the error-reason

lemma = wordnet_lemmatizer.lemmatize(word,word_pos)

import nltk
from nltk.corpus import PlaintextCorpusReader
from nltk import sent_tokenize, word_tokenize, pos_tag
from nltk.stem import WordNetLemmatizer
wordnet_lemmatizer = WordNetLemmatizer()

corpus_root = 'C:\\Users\\myname\\Desktop\\TestCorpus'
lyrics = PlaintextCorpusReader(corpus_root,'.*')

for fileid in lyrics.fileids():
     tokens = word_tokenize(lyrics.raw(fileid))
     tagged_tokens = pos_tag(tokens)
     for tagged_token in tagged_tokens:
         word = tagged_token[0]
         word_pos = tagged_token[1]
         print(tagged_token[0])
         print(tagged_token[1])
         lemma = wordnet_lemmatizer.lemmatize(word,pos=word_pos)
         print(lemma)

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Additional Question: Is the pos_tag enough for my lemmatization or need i another tagger? My texts are lyrics...

Answer 1

You need to convert the tag from the pos_tagger to one of the four "syntactic categories" that wordnet recognizes, then pass that to the lemmatizer as the word_pos.

From the docs:

Syntactic category: n for noun files, v for verb files, a for adjective files, r for adverb files.