dataobject.py

# special error message
class MyIOError(Exception):
    def __init__(self, filename):
        # custom error message
        message = """
ERROR: Unable to locate file {}.

FIX: Have you tried running python build_data.py first?
This will build vocab file from your train, test and dev sets and
trimm your word vectors.
""".format(filename)
        super(MyIOError, self).__init__(message)


class CoNLLDataset(object):
    """Class that iterates over CoNLL Dataset

    __iter__ method yields a tuple (words, tags)
        words: list of raw words
        tags: list of raw tags

    If processing_word and processing_tag are not None,
    optional preprocessing is appplied

    Example:
        ```python
        data = CoNLLDataset(filename)
        for sentence, tags in data:
            pass
        ```

    """
    def __init__(self, filename, processing_word=None, processing_tag=None,
                 max_iter=None):
        """
        Args:
            filename: path to the file
            processing_words: (optional) function that takes a word as input
            processing_tags: (optional) function that takes a tag as input
            max_iter: (optional) max number of sentences to yield

        """
        self.filename = filename
        self.processing_word = processing_word
        self.processing_tag = processing_tag
        self.max_iter = max_iter
        self.length = None


    def __iter__(self):
        niter = 0
        with open(self.filename) as f:
            words, tags = [], []
            for line in f:
                line = line.strip()
                if (len(line) == 0 or line.startswith("-DOCSTART-")):
                    if len(words) != 0:
                        niter += 1
                        if self.max_iter is not None and niter > self.max_iter:
                            break
                        yield words, tags
                        words, tags = [], []
                else:
                    ls = line.split(' ')
                    word, tag = ls[0],ls[-1]
                    if self.processing_word is not None:
                        word = self.processing_word(word)
                    if self.processing_tag is not None:
                        tag = self.processing_tag(tag)
                    words += [word]
                    tags += [tag]


    def __len__(self):
        """Iterates once over the corpus to set and store length"""
        if self.length is None:
            self.length = 0
            for _ in self:
                self.length += 1

        return self.length