This repository contains an R package which wraps the CRFsuite C/C++ library (https://github.com/chokkan/crfsuite), allowing the following:
For users unfamiliar with Conditional Random Field (CRF) models, you can read this excellent tutorial http://homepages.inf.ed.ac.uk/csutton/publications/crftut-fnt.pdf
devtools::install_github("bnosac/crfsuite", build_vignettes = TRUE)
For detailed documentation on how to build your own CRF tagger for doing NER / Chunking. Look to the vignette.
library(crfsuite) vignette("crfsuite-nlp", package = "crfsuite")
library(crfsuite) ## Get example training data + enrich with token and part of speech 2 words before/after each token x <- ner_download_modeldata("conll2002-nl") x <- crf_cbind_attributes(x, terms = c("token", "pos"), by = c("doc_id", "sentence_id"), from = -2, to = 2, ngram_max = 3, sep = "-") ## Split in train/test set crf_train <- subset(x, data == "ned.train") crf_test <- subset(x, data == "testa") ## Build the crf model attributes <- grep("token|pos", colnames(x), value=TRUE) model <- crf(y = crf_train$label, x = crf_train[, attributes], group = crf_train$doc_id, method = "lbfgs", options = list(max_iterations = 25, feature.minfreq = 5, c1 = 0, c2 = 1)) model ## Use the model to score on existing tokenised data scores <- predict(model, newdata = crf_test[, attributes], group = crf_test$doc_id) table(scores$label) B-LOC B-MISC B-ORG B-PER I-LOC I-MISC I-ORG I-PER O 261 211 182 693 24 205 209 605 35297
The package itself does not contain any models to do NER or Chunking. It's a package which facilitates creating your own CRF model for doing Named Entity Recognition or Chunking on your own data with your own categories.
In order to facilitate creating training data of your own text, a shiny app is made available in this R package which allows you to easily tag your own chunks of text, using your own categories.
More details about how to launch the app, which data is needed for building a model, how to start to build and use your model - read the vignette in detail:
vignette("crfsuite-nlp", package = "crfsuite").
Need support in text mining? Contact BNOSAC: http://www.bnosac.be
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