Trjtdtk

I'm new to NLP.
I have a folder containing .txt files which are legal and specific documents. I want to label all these files based on four predefined labels. How can I do that automatically?

The task you have is called named-entity recognition. From wiki:

Named-entity recognition (NER) (also known as entity identification, entity chunking and entity extraction) is a subtask of information extraction that seeks to locate and classify named entity mentions in unstructured text into pre-defined categories such as the person names, organizations, locations, medical codes, time expressions, quantities, monetary values, percentages, etc.

Since this is a common NLP task there are libraries that are made to do NER out of the box. One such library is spaCy which can do NER as well as many other NLP tasks using Python.

You will not be able to perform NER without first training a model on your custom labels/entities. You need to have some labelled data to train on, maybe you already have this or you can label it manually. SpaCy wants yo have the data labelled with location of each entity on the format:

[("legal text here", "entities": [(Start index, End index, "Money"), 
 (Start index, End index, "Judge"), 
 (Start index, End index, "Tribunal"), 
 (Start index, End index, "State")]),
("legal text here", "entities": [(Start index, End index, "Money"), 
 (Start index, End index, "Judge"), 
 (Start index, End index, "Tribunal"), 
 (Start index, End index, "State")])
...]

Example on how to training a spaCy model for NER (taken from docs):

from __future__ import unicode_literals, print_function

import plac
import random
from pathlib import Path
import spacy
from spacy.util import minibatch, compounding 

# training data
TRAIN_DATA = Insert you labelled training data here 

@plac.annotations(
 model=("Model name. Defaults to blank 'en' model.", "option", "m", str),
 output_dir=("Optional output directory", "option", "o", Path),
 n_iter=("Number of training iterations", "option", "n", int),
)
def main(model=None, output_dir=None, n_iter=100):
 """Load the model, set up the pipeline and train the entity recognizer."""
 if model is not None:
 nlp = spacy.load(model) # load existing spaCy model
 print("Loaded model '%s'" % model)
 else:
 nlp = spacy.blank("en") # create blank Language class
 print("Created blank 'en' model")

 # create the built-in pipeline components and add them to the pipeline
 # nlp.create_pipe works for built-ins that are registered with spaCy
 if "ner" not in nlp.pipe_names:
 ner = nlp.create_pipe("ner")
 nlp.add_pipe(ner, last=True)
 # otherwise, get it so we can add labels
 else:
 ner = nlp.get_pipe("ner")

 # add labels
 for _, annotations in TRAIN_DATA:
 for ent in annotations.get("entities"):
 ner.add_label(ent[2])

 # get names of other pipes to disable them during training
 other_pipes = [pipe for pipe in nlp.pipe_names if pipe != "ner"]
 with nlp.disable_pipes(*other_pipes): # only train NER
 # reset and initialize the weights randomly – but only if we're
 # training a new model
 if model is None:
 nlp.begin_training()
 for itn in range(n_iter):
 random.shuffle(TRAIN_DATA)
 losses = 
 # batch up the examples using spaCy's minibatch
 batches = minibatch(TRAIN_DATA, size=compounding(4.0, 32.0, 1.001))
 for batch in batches:
 texts, annotations = zip(*batch)
 nlp.update(
 texts, # batch of texts
 annotations, # batch of annotations
 drop=0.5, # dropout - make it harder to memorise data
 losses=losses,
 )
 print("Losses", losses)

 # test the trained model
 for text, _ in TRAIN_DATA:
 doc = nlp(text)
 print("Entities", [(ent.text, ent.label_) for ent in doc.ents])
 print("Tokens", [(t.text, t.ent_type_, t.ent_iob) for t in doc])

 # save model to output directory
 if output_dir is not None:
 output_dir = Path(output_dir)
 if not output_dir.exists():
 output_dir.mkdir()
 nlp.to_disk(output_dir)
 print("Saved model to", output_dir)

 # test the saved model
 print("Loading from", output_dir)
 nlp2 = spacy.load(output_dir)
 for text, _ in TRAIN_DATA:
 doc = nlp2(text)
 print("Entities", [(ent.text, ent.label_) for ent in doc.ents])
 print("Tokens", [(t.text, t.ent_type_, t.ent_iob) for t in doc])


if __name__ == "__main__":
 plac.call(main)

Then when you have a trained model you can use it to get your entities:

doc = nlp('put legal text to test your model here')

for ent in doc.ents:
 print(ent.text, ent.start_char, ent.end_char, ent.label_)