#!/usr/bin/env python

import argparse, collections, functools, itertools, math, operator, os.path, re, string, sys

import nltk.data

import nltk_trainer.classification.args

from nltk.classify import DecisionTreeClassifier, MaxentClassifier, NaiveBayesClassifier

from nltk.classify.util import accuracy

from nltk.corpus import stopwords

from nltk.corpus.reader import CategorizedPlaintextCorpusReader, CategorizedTaggedCorpusReader

from nltk.corpus.util import LazyCorpusLoader

from nltk.metrics import BigramAssocMeasures, f_measure, masi_distance, precision, recall

from nltk.probability import FreqDist, ConditionalFreqDist

from nltk.util import ngrams

from nltk_trainer import dump_object, import_attr, iteritems, load_corpus_reader

from nltk_trainer.classification import corpus, scoring

from nltk_trainer.classification.featx import (bag_of_words, bag_of_words_in_set,

word_counts, train_test_feats, word_counts_in_set)

from nltk_trainer.classification.multi import MultiBinaryClassifier

########################################

## command options & argument parsing ##

########################################

parser = argparse.ArgumentParser(description='Train a NLTK Classifier')

parser.add_argument('corpus', help='corpus name/path relative to an nltk_data directory')

parser.add_argument('--filename', help='''filename/path for where to store the

pickled classifier, the default is {corpus}_{algorithm}.pickle in

~/nltk_data/classifiers''')

parser.add_argument('--no-pickle', action='store_true', default=False,

help="don't pickle and save the classifier")

parser.add_argument('--classifier', '--algorithm', default=['NaiveBayes'], nargs='+',

choices=nltk_trainer.classification.args.classifier_choices,

help='''Classifier algorithm to use, defaults to %(default)s. Maxent uses the

default Maxent training algorithm, either CG or iis.''')

parser.add_argument('--trace', default=1, type=int,

help='How much trace output you want, defaults to 1. 0 is no trace output.')

parser.add_argument('--show-most-informative', default=0, type=int,

help='number of most informative features to show, works for all algorithms except DecisionTree')

corpus_group = parser.add_argument_group('Training Corpus')

corpus_group.add_argument('--reader',

default='nltk.corpus.reader.CategorizedPlaintextCorpusReader',

help='Full module path to a corpus reader class, such as %(default)s')

corpus_group.add_argument('--cat_pattern', default='(.+)/.+',

help='''A regular expression pattern to identify categories based on file paths.

If cat_file is also given, this pattern is used to identify corpus file ids.

The default is '(.+)/+', which uses sub-directories as categories.''')

corpus_group.add_argument('--cat_file',

help='relative path to a file containing category listings')

corpus_group.add_argument('--delimiter', default=' ',

help='category delimiter for category file, defaults to space')

corpus_group.add_argument('--instances', default='files',

choices=('sents', 'paras', 'files'),

help='''the group of words that represents a single training instance,

the default is to use entire files''')

corpus_group.add_argument('--fraction', default=1.0, type=float,

help='''The fraction of the corpus to use for training a binary or

multi-class classifier, the rest will be used for evaulation.

The default is to use the entire corpus, and to test the classifier

against the same training data. Any number < 1 will test against

the remaining fraction.''')

corpus_group.add_argument('--train-prefix', default=None,

help='optional training fileid prefix for multi classifiers')

corpus_group.add_argument('--test-prefix', default=None,

help='optional testing fileid prefix for multi classifiers')

corpus_group.add_argument('--word-tokenizer', default='', help='Word Tokenizer class path')

corpus_group.add_argument('--sent-tokenizer', default='', help='Sent Tokenizer data.pickle path')

corpus_group.add_argument('--para-block-reader', default='', help='Block reader function path')

corpus_group.add_argument('--labels', default=[],

help='''If given a list of labels, default categories by corpus are omitted''')

classifier_group = parser.add_argument_group('Classifier Type',

binary classifiers, 1 for each label.''')

classifier_group.add_argument('--binary', action='store_true', default=False,

help='train a binary classifier, or a multi-binary classifier if --multi is also given')

classifier_group.add_argument('--multi', action='store_true', default=False,

help='train a multi-class classifier, or a multi-binary classifier if --binary is also given')

feat_group = parser.add_argument_group('Feature Extraction',

'The default is to lowercase every word, strip punctuation, and use stopwords')

feat_group.add_argument('--ngrams', nargs='+', type=int,

help='use n-grams as features.')

feat_group.add_argument('--no-lowercase', action='store_true', default=False,

help="don't lowercase every word")

feat_group.add_argument('--filter-stopwords', default='no',

choices=['no']+stopwords.fileids(),

help='language stopwords to filter, defaults to "no" to keep stopwords')

feat_group.add_argument('--punctuation', action='store_true', default=False,

help="don't strip punctuation")

feat_group.add_argument('--value-type', default='bool', choices=('bool', 'int', 'float'),

help='''Data type of values in featuresets. The default is bool, which ignores word counts.

Use int to get word and/or ngram counts.''')

score_group = parser.add_argument_group('Feature Scoring',

'The default is no scoring, all words are included as features')

score_group.add_argument('--score_fn', default='chi_sq',

choices=[f for f in dir(BigramAssocMeasures) if not f.startswith('_')],

help='scoring function for information gain and bigram collocations, defaults to chi_sq')

score_group.add_argument('--min_score', default=0, type=int,

help='minimum score for a word to be included, default is 0 to include all words')

score_group.add_argument('--max_feats', default=0, type=int,

help='maximum number of words to include, ordered by highest score, defaults is 0 to include all words')

eval_group = parser.add_argument_group('Classifier Evaluation',

'''The default is to test the classifier against the unused fraction of the

corpus, or against the entire corpus if the whole corpus is used for training.''')

eval_group.add_argument('--no-eval', action='store_true', default=False,

help="don't do any evaluation")

eval_group.add_argument('--no-accuracy', action='store_true', default=False,

help="don't evaluate accuracy")

eval_group.add_argument('--no-precision', action='store_true', default=False,

help="don't evaluate precision")

eval_group.add_argument('--no-recall', action='store_true', default=False,

help="don't evaluate recall")

eval_group.add_argument('--no-fmeasure', action='store_true', default=False,

help="don't evaluate f-measure")

eval_group.add_argument('--no-masi-distance', action='store_true', default=False,

help="don't evaluate masi distance (only applies to a multi binary classifier)")

eval_group.add_argument('--cross-fold', type=int, default=0,

help='''If given a number greater than 2, will do cross fold validation

instead of normal training and testing. This option implies --no-pickle,

is useless with --trace 0 and/or --no-eval, and currently does not work

with --multi --binary.

''')

nltk_trainer.classification.args.add_maxent_args(parser)

nltk_trainer.classification.args.add_decision_tree_args(parser)

nltk_trainer.classification.args.add_sklearn_args(parser)

args = parser.parse_args()

###################

## corpus reader ##

###################

reader_args = []

reader_kwargs = {}

if args.cat_file:

reader_kwargs['cat_file'] = args.cat_file

if args.delimiter and args.delimiter != ' ':

reader_kwargs['delimiter'] = args.delimiter

if args.cat_pattern:

reader_args.append(args.cat_pattern)

else:

reader_args.append('.+/.+')

elif args.cat_pattern:

reader_args.append(args.cat_pattern)

reader_kwargs['cat_pattern'] = re.compile(args.cat_pattern)

if args.word_tokenizer:

reader_kwargs['word_tokenizer'] = import_attr(args.word_tokenizer)()

if args.sent_tokenizer:

reader_kwargs['sent_tokenizer'] = nltk.data.LazyLoader(args.sent_tokenizer)

if args.para_block_reader:

reader_kwargs['para_block_reader'] = import_attr(args.para_block_reader)

if args.trace:

print('loading %s' % args.corpus)

categorized_corpus = load_corpus_reader(args.corpus, args.reader,

*reader_args, **reader_kwargs)

if not hasattr(categorized_corpus, 'categories'):

raise ValueError('%s is does not have categories for classification')

if len(args.labels) > 0:

labels = args.labels.split(",")

else:

labels = categorized_corpus.categories()

nlabels = len(labels)

if args.trace:

print('%d labels: %s' % (nlabels, labels))

if not nlabels:

raise ValueError('corpus does not have any categories')

elif nlabels == 1:

raise ValueError('corpus must have more than 1 category')

elif nlabels == 2 and args.multi:

raise ValueError('corpus must have more than 2 categories if --multi is specified')

########################

## text normalization ##

########################

if args.filter_stopwords == 'no':

stopset = set()

else:

stopset = set(stopwords.words(args.filter_stopwords))

def norm_words(words):

return words

#####################

## text extraction ##

#####################

if args.multi and args.binary:

label_instance_function = {

'sents': corpus.multi_category_sent_words,

'paras': corpus.multi_category_para_words,

'files': corpus.multi_category_file_words

}

lif = label_instance_function[args.instances]

train_instances = lif(categorized_corpus, args.train_prefix)

test_instances = lif(categorized_corpus, args.test_prefix)

# if we need all the words by category for score_fn, use this method

def category_words():

return iteritems(cat_words)

else:

def split_list(lis, fraction):

return lis, []

label_instance_function = {

'sents': corpus.category_sent_words,

'paras': corpus.category_para_words,

'files': corpus.category_file_words

}

lif = label_instance_function[args.instances]

train_instances = {}

test_instances = {}

for label in labels:

instances = (norm_words(i) for i in lif(categorized_corpus, label))

instances = [i for i in instances if i]

train_instances[label], test_instances[label] = split_list(instances, args.fraction)

if args.trace > 1:

info = (label, len(train_instances[label]), len(test_instances[label]))

print('%s: %d training instances, %d testing instances' % info)

# if we need all the words by category for score_fn, use this method

def category_words():

return ((cat, (word for i in instance_list for word in i)) for cat, instance_list in iteritems(train_instances))

##################

## word scoring ##

##################

score_fn = getattr(BigramAssocMeasures, args.score_fn)

if args.min_score or args.max_feats:

if args.trace:

print('calculating word scores')

# flatten the list of instances to a single iteration of all the words

cat_words = category_words()

ws = scoring.sorted_word_scores(scoring.sum_category_word_scores(cat_words, score_fn))

if args.min_score:

ws = [(w, s) for (w, s) in ws if s >= args.min_score]

if args.max_feats:

ws = ws[:args.max_feats]

bestwords = set([w for (w, s) in ws])

if args.value_type == 'bool':

if args.trace:

print('using bag of words from known set feature extraction')

featx = lambda words: bag_of_words_in_set(words, bestwords)

else:

if args.trace:

print('using word counts from known set feature extraction')

featx = lambda words: word_counts_in_set(words, bestwords)

if args.trace:

print('%d words meet min_score and/or max_feats' % len(bestwords))

elif args.value_type == 'bool':

if args.trace:

print('using bag of words feature extraction')

featx = bag_of_words

else:

if args.trace:

print('using word counts feature extraction')

featx = word_counts

#########################

## extracting features ##

#########################

def extract_features(label_instances, featx):

return feats

train_feats = extract_features(train_instances, featx)

test_feats = extract_features(test_instances, featx)

# if there were no instances reserved for testing, test over the whole training set

if not test_feats:

test_feats = train_feats

if args.trace:

print('%d training feats, %d testing feats' % (len(train_feats), len(test_feats)))

##############

## training ##

##############

trainf = nltk_trainer.classification.args.make_classifier_builder(args)

if args.cross_fold:

if args.multi and args.binary:

raise NotImplementedError ("cross-fold is not supported for multi-binary classifiers")

scoring.cross_fold(train_feats, trainf, accuracy, folds=args.cross_fold,

trace=args.trace, metrics=not args.no_eval, informative=args.show_most_informative)

sys.exit(0)

if args.multi and args.binary:

if args.trace:

print('training multi-binary %s classifier' % args.classifier)

classifier = MultiBinaryClassifier.train(labels, train_feats, trainf)

else:

classifier = trainf(train_feats)

################

## evaluation ##

################

if not args.no_eval:

if not args.no_accuracy:

try:

print('accuracy: %f' % accuracy(classifier, test_feats))

except ZeroDivisionError:

print('accuracy: 0')

if args.multi and args.binary and not args.no_masi_distance:

print('average masi distance: %f' % (scoring.avg_masi_distance(classifier, test_feats)))

if not args.no_precision or not args.no_recall or not args.no_fmeasure:

if args.multi and args.binary:

refsets, testsets = scoring.multi_ref_test_sets(classifier, test_feats)

else:

refsets, testsets = scoring.ref_test_sets(classifier, test_feats)

for label in labels:

ref = refsets[label]

test = testsets[label]

if not args.no_precision:

print('%s precision: %f' % (label, precision(ref, test) or 0))

if not args.no_recall:

print('%s recall: %f' % (label, recall(ref, test) or 0))

if not args.no_fmeasure:

print('%s f-measure: %f' % (label, f_measure(ref, test) or 0))

if args.show_most_informative and hasattr(classifier, 'show_most_informative_features') and not (args.multi and args.binary) and not args.cross_fold:

print('%d most informative features' % args.show_most_informative)

classifier.show_most_informative_features(args.show_most_informative)

##############

## pickling ##

##############

if not args.no_pickle:

if args.filename:

fname = os.path.expanduser(args.filename)

else:

name = '%s_%s.pickle' % (args.corpus, '_'.join(args.classifier))

fname = os.path.join(os.path.expanduser('~/nltk_data/classifiers'), name)

dump_object(classifier, fname, trace=args.trace)