/
utils.py
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/
utils.py
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#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# Copyright (C) 2010 Radim Rehurek <radimrehurek@seznam.cz>
# Licensed under the GNU LGPL v2.1 - http://www.gnu.org/licenses/lgpl.html
"""This module contains various general utility functions."""
from __future__ import with_statement
from contextlib import contextmanager
import collections
import logging
import warnings
try:
from html.entities import name2codepoint as n2cp
except ImportError:
from htmlentitydefs import name2codepoint as n2cp
try:
import cPickle as _pickle
except ImportError:
import pickle as _pickle
import re
import unicodedata
import os
import random
import itertools
import tempfile
from functools import wraps
import multiprocessing
import shutil
import sys
import subprocess
import inspect
import numpy as np
import numbers
import scipy.sparse
from six import iterkeys, iteritems, u, string_types, unichr
from six.moves import xrange
from smart_open import smart_open
if sys.version_info[0] >= 3:
unicode = str
logger = logging.getLogger(__name__)
PAT_ALPHABETIC = re.compile(r'(((?![\d])\w)+)', re.UNICODE)
RE_HTML_ENTITY = re.compile(r'&(#?)([xX]?)(\w{1,8});', re.UNICODE)
def get_random_state(seed):
"""Generate :class:`numpy.random.RandomState` based on input seed.
Parameters
----------
seed : {None, int, array_like}
Seed for random state.
Returns
-------
:class:`numpy.random.RandomState`
Random state.
Raises
------
AttributeError
If seed is not {None, int, array_like}.
Notes
-----
Method originally from [1]_ and written by @joshloyal.
References
----------
.. [1] https://github.com/maciejkula/glove-python
"""
if seed is None or seed is np.random:
return np.random.mtrand._rand
if isinstance(seed, (numbers.Integral, np.integer)):
return np.random.RandomState(seed)
if isinstance(seed, np.random.RandomState):
return seed
raise ValueError('%r cannot be used to seed a np.random.RandomState instance' % seed)
def synchronous(tlockname):
"""A decorator to place an instance-based lock around a method.
Notes
-----
Adapted from [2]_
References
----------
.. [2] http://code.activestate.com/recipes/577105-synchronization-decorator-for-class-methods/
"""
def _synched(func):
@wraps(func)
def _synchronizer(self, *args, **kwargs):
tlock = getattr(self, tlockname)
logger.debug("acquiring lock %r for %s", tlockname, func.__name__)
with tlock: # use lock as a context manager to perform safe acquire/release pairs
logger.debug("acquired lock %r for %s", tlockname, func.__name__)
result = func(self, *args, **kwargs)
logger.debug("releasing lock %r for %s", tlockname, func.__name__)
return result
return _synchronizer
return _synched
def file_or_filename(input):
"""Open file with `smart_open`.
Parameters
----------
input : str or file-like
Filename or file-like object.
Returns
-------
input : file-like object
Opened file OR seek out to 0 byte if `input` is already file-like object.
"""
if isinstance(input, string_types):
# input was a filename: open as file
return smart_open(input)
else:
# input already a file-like object; just reset to the beginning
input.seek(0)
return input
@contextmanager
def open_file(input):
"""Provide "with-like" behaviour except closing the file object.
Parameters
----------
input : str or file-like
Filename or file-like object.
Yields
-------
file
File-like object based on input (or input if this already file-like).
"""
mgr = file_or_filename(input)
exc = False
try:
yield mgr
except Exception:
# Handling any unhandled exceptions from the code nested in 'with' statement.
exc = True
if not isinstance(input, string_types) or not mgr.__exit__(*sys.exc_info()):
raise
# Try to introspect and silence errors.
finally:
if not exc and isinstance(input, string_types):
mgr.__exit__(None, None, None)
def deaccent(text):
"""Remove accentuation from the given string.
Parameters
----------
text : str
Input string.
Returns
-------
str
Unicode string without accentuation.
Examples
--------
>>> from gensim.utils import deaccent
>>> deaccent("Šéf chomutovských komunistů dostal poštou bílý prášek")
u'Sef chomutovskych komunistu dostal postou bily prasek'
"""
if not isinstance(text, unicode):
# assume utf8 for byte strings, use default (strict) error handling
text = text.decode('utf8')
norm = unicodedata.normalize("NFD", text)
result = u('').join(ch for ch in norm if unicodedata.category(ch) != 'Mn')
return unicodedata.normalize("NFC", result)
def copytree_hardlink(source, dest):
"""Recursively copy a directory ala shutils.copytree, but hardlink files instead of copying.
Parameters
----------
source : str
Path to source directory
dest : str
Path to destination directory
Warnings
--------
Available on UNIX systems only.
"""
copy2 = shutil.copy2
try:
shutil.copy2 = os.link
shutil.copytree(source, dest)
finally:
shutil.copy2 = copy2
def tokenize(text, lowercase=False, deacc=False, encoding='utf8', errors="strict", to_lower=False, lower=False):
"""Iteratively yield tokens as unicode strings, removing accent marks and optionally lowercasing string
if any from `lowercase`, `to_lower`, `lower` set to True.
Parameters
----------
text : str
Input string.
lowercase : bool, optional
If True - lowercase input string.
deacc : bool, optional
If True - remove accentuation from string by :func:`~gensim.utils.deaccent`.
encoding : str, optional
Encoding of input string, used as parameter for :func:`~gensim.utils.to_unicode`.
errors : str, optional
Error handling behaviour, used as parameter for :func:`~gensim.utils.to_unicode`.
to_lower : bool, optional
Same as `lowercase`.
lower : bool, optional
Same as `lowercase`.
Yields
------
str
Contiguous sequences of alphabetic characters (no digits!), using :func:`~gensim.utils.simple_tokenize`
Examples
--------
>>> from gensim.utils import tokenize
>>> list(tokenize('Nic nemůže letět rychlostí vyšší, než 300 tisíc kilometrů za sekundu!', deacc=True))
[u'Nic', u'nemuze', u'letet', u'rychlosti', u'vyssi', u'nez', u'tisic', u'kilometru', u'za', u'sekundu']
"""
lowercase = lowercase or to_lower or lower
text = to_unicode(text, encoding, errors=errors)
if lowercase:
text = text.lower()
if deacc:
text = deaccent(text)
return simple_tokenize(text)
def simple_tokenize(text):
"""Tokenize input test using :const:`gensim.utils.PAT_ALPHABETIC`.
Parameters
----------
text : str
Input text.
Yields
------
str
Tokens from `text`.
"""
for match in PAT_ALPHABETIC.finditer(text):
yield match.group()
def simple_preprocess(doc, deacc=False, min_len=2, max_len=15):
"""Convert a document into a list of tokens (also with lowercase and optional de-accents),
used :func:`~gensim.utils.tokenize`.
Parameters
----------
doc : str
Input document.
deacc : bool, optional
If True - remove accentuation from string by :func:`~gensim.utils.deaccent`.
min_len : int, optional
Minimal length of token in result (inclusive).
max_len : int, optional
Maximal length of token in result (inclusive).
Returns
-------
list of str
Tokens extracted from `doc`.
"""
tokens = [
token for token in tokenize(doc, lower=True, deacc=deacc, errors='ignore')
if min_len <= len(token) <= max_len and not token.startswith('_')
]
return tokens
def any2utf8(text, errors='strict', encoding='utf8'):
"""Convert `text` to bytestring in utf8.
Parameters
----------
text : str
Input text.
errors : str, optional
Error handling behaviour, used as parameter for `unicode` function (python2 only).
encoding : str, optional
Encoding of `text` for `unicode` function (python2 only).
Returns
-------
str
Bytestring in utf8.
"""
if isinstance(text, unicode):
return text.encode('utf8')
# do bytestring -> unicode -> utf8 full circle, to ensure valid utf8
return unicode(text, encoding, errors=errors).encode('utf8')
to_utf8 = any2utf8
def any2unicode(text, encoding='utf8', errors='strict'):
"""Convert `text` to unicode.
Parameters
----------
text : str
Input text.
errors : str, optional
Error handling behaviour, used as parameter for `unicode` function (python2 only).
encoding : str, optional
Encoding of `text` for `unicode` function (python2 only).
Returns
-------
str
Unicode version of `text`.
"""
if isinstance(text, unicode):
return text
return unicode(text, encoding, errors=errors)
to_unicode = any2unicode
def call_on_class_only(*args, **kwargs):
"""Helper for raise `AttributeError` if method should be called from instance.
Parameters
----------
*args
Variable length argument list.
**kwargs
Arbitrary keyword arguments.
Raises
------
AttributeError
If `load` method are called on instance.
"""
raise AttributeError('This method should be called on a class object.')
class SaveLoad(object):
"""Class which inherit from this class have save/load functions, which un/pickle them to disk.
Warnings
--------
This uses pickle for de/serializing, so objects must not contain unpicklable attributes,
such as lambda functions etc.
"""
@classmethod
def load(cls, fname, mmap=None):
"""Load a previously saved object (using :meth:`~gensim.utils.SaveLoad.save`) from file.
Parameters
----------
fname : str
Path to file that contains needed object.
mmap : str, optional
Memory-map option. If the object was saved with large arrays stored separately, you can load these arrays
via mmap (shared memory) using `mmap='r'.
If the file being loaded is compressed (either '.gz' or '.bz2'), then `mmap=None` **must be** set.
See Also
--------
:meth:`~gensim.utils.SaveLoad.save`
Returns
-------
object
Object loaded from `fname`.
Raises
------
IOError
When methods are called on instance (should be called from class).
"""
logger.info("loading %s object from %s", cls.__name__, fname)
compress, subname = SaveLoad._adapt_by_suffix(fname)
obj = unpickle(fname)
obj._load_specials(fname, mmap, compress, subname)
logger.info("loaded %s", fname)
return obj
def _load_specials(self, fname, mmap, compress, subname):
"""Loads any attributes that were stored specially, and gives the same opportunity
to recursively included :class:`~gensim.utils.SaveLoad` instances.
Parameters
----------
fname : str
Path to file that contains needed object.
mmap : str
Memory-map option.
compress : bool
Set to True if file is compressed.
subname : str
...
"""
def mmap_error(obj, filename):
return IOError(
'Cannot mmap compressed object %s in file %s. ' % (obj, filename) +
'Use `load(fname, mmap=None)` or uncompress files manually.'
)
for attrib in getattr(self, '__recursive_saveloads', []):
cfname = '.'.join((fname, attrib))
logger.info("loading %s recursively from %s.* with mmap=%s", attrib, cfname, mmap)
getattr(self, attrib)._load_specials(cfname, mmap, compress, subname)
for attrib in getattr(self, '__numpys', []):
logger.info("loading %s from %s with mmap=%s", attrib, subname(fname, attrib), mmap)
if compress:
if mmap:
raise mmap_error(attrib, subname(fname, attrib))
val = np.load(subname(fname, attrib))['val']
else:
val = np.load(subname(fname, attrib), mmap_mode=mmap)
setattr(self, attrib, val)
for attrib in getattr(self, '__scipys', []):
logger.info("loading %s from %s with mmap=%s", attrib, subname(fname, attrib), mmap)
sparse = unpickle(subname(fname, attrib))
if compress:
if mmap:
raise mmap_error(attrib, subname(fname, attrib))
with np.load(subname(fname, attrib, 'sparse')) as f:
sparse.data = f['data']
sparse.indptr = f['indptr']
sparse.indices = f['indices']
else:
sparse.data = np.load(subname(fname, attrib, 'data'), mmap_mode=mmap)
sparse.indptr = np.load(subname(fname, attrib, 'indptr'), mmap_mode=mmap)
sparse.indices = np.load(subname(fname, attrib, 'indices'), mmap_mode=mmap)
setattr(self, attrib, sparse)
for attrib in getattr(self, '__ignoreds', []):
logger.info("setting ignored attribute %s to None", attrib)
setattr(self, attrib, None)
@staticmethod
def _adapt_by_suffix(fname):
"""Give appropriate compress setting and filename formula.
Parameters
----------
fname : str
Input filename.
Returns
-------
(bool, function)
First argument will be True if `fname` compressed.
"""
compress, suffix = (True, 'npz') if fname.endswith('.gz') or fname.endswith('.bz2') else (False, 'npy')
return compress, lambda *args: '.'.join(args + (suffix,))
def _smart_save(self, fname, separately=None, sep_limit=10 * 1024**2, ignore=frozenset(), pickle_protocol=2):
"""Save the object to file.
Parameters
----------
fname : str
Path to file.
separately : list, optional
Iterable of attributes than need to store distinctly.
sep_limit : int, optional
Limit for separation.
ignore : frozenset, optional
Attributes that shouldn't be store.
pickle_protocol : int, optional
Protocol number for pickle.
Notes
-----
If `separately` is None, automatically detect large
numpy/scipy.sparse arrays in the object being stored, and store
them into separate files. This avoids pickle memory errors and
allows mmap'ing large arrays back on load efficiently.
You can also set `separately` manually, in which case it must be
a list of attribute names to be stored in separate files. The
automatic check is not performed in this case.
See Also
--------
:meth:`~gensim.utils.SaveLoad.load`
"""
logger.info("saving %s object under %s, separately %s", self.__class__.__name__, fname, separately)
compress, subname = SaveLoad._adapt_by_suffix(fname)
restores = self._save_specials(fname, separately, sep_limit, ignore, pickle_protocol,
compress, subname)
try:
pickle(self, fname, protocol=pickle_protocol)
finally:
# restore attribs handled specially
for obj, asides in restores:
for attrib, val in iteritems(asides):
setattr(obj, attrib, val)
logger.info("saved %s", fname)
def _save_specials(self, fname, separately, sep_limit, ignore, pickle_protocol, compress, subname):
"""Save aside any attributes that need to be handled separately, including
by recursion any attributes that are themselves :class:`~gensim.utils.SaveLoad` instances.
Parameters
----------
fname : str
Output filename.
separately : list or None
Iterable of attributes than need to store distinctly
sep_limit : int
Limit for separation.
ignore : iterable of str
Attributes that shouldn't be store.
pickle_protocol : int
Protocol number for pickle.
compress : bool
If True - compress output with :func:`numpy.savez_compressed`.
subname : function
Produced by :meth:`~gensim.utils.SaveLoad._adapt_by_suffix`
Returns
-------
list of (obj, {attrib: value, ...})
Settings that the caller should use to restore each object's attributes that were set aside
during the default :func:`~gensim.utils.pickle`.
"""
asides = {}
sparse_matrices = (scipy.sparse.csr_matrix, scipy.sparse.csc_matrix)
if separately is None:
separately = []
for attrib, val in iteritems(self.__dict__):
if isinstance(val, np.ndarray) and val.size >= sep_limit:
separately.append(attrib)
elif isinstance(val, sparse_matrices) and val.nnz >= sep_limit:
separately.append(attrib)
# whatever's in `separately` or `ignore` at this point won't get pickled
for attrib in separately + list(ignore):
if hasattr(self, attrib):
asides[attrib] = getattr(self, attrib)
delattr(self, attrib)
recursive_saveloads = []
restores = []
for attrib, val in iteritems(self.__dict__):
if hasattr(val, '_save_specials'): # better than 'isinstance(val, SaveLoad)' if IPython reloading
recursive_saveloads.append(attrib)
cfname = '.'.join((fname, attrib))
restores.extend(val._save_specials(cfname, None, sep_limit, ignore, pickle_protocol, compress, subname))
try:
numpys, scipys, ignoreds = [], [], []
for attrib, val in iteritems(asides):
if isinstance(val, np.ndarray) and attrib not in ignore:
numpys.append(attrib)
logger.info("storing np array '%s' to %s", attrib, subname(fname, attrib))
if compress:
np.savez_compressed(subname(fname, attrib), val=np.ascontiguousarray(val))
else:
np.save(subname(fname, attrib), np.ascontiguousarray(val))
elif isinstance(val, (scipy.sparse.csr_matrix, scipy.sparse.csc_matrix)) and attrib not in ignore:
scipys.append(attrib)
logger.info("storing scipy.sparse array '%s' under %s", attrib, subname(fname, attrib))
if compress:
np.savez_compressed(
subname(fname, attrib, 'sparse'),
data=val.data,
indptr=val.indptr,
indices=val.indices
)
else:
np.save(subname(fname, attrib, 'data'), val.data)
np.save(subname(fname, attrib, 'indptr'), val.indptr)
np.save(subname(fname, attrib, 'indices'), val.indices)
data, indptr, indices = val.data, val.indptr, val.indices
val.data, val.indptr, val.indices = None, None, None
try:
# store array-less object
pickle(val, subname(fname, attrib), protocol=pickle_protocol)
finally:
val.data, val.indptr, val.indices = data, indptr, indices
else:
logger.info("not storing attribute %s", attrib)
ignoreds.append(attrib)
self.__dict__['__numpys'] = numpys
self.__dict__['__scipys'] = scipys
self.__dict__['__ignoreds'] = ignoreds
self.__dict__['__recursive_saveloads'] = recursive_saveloads
except Exception:
# restore the attributes if exception-interrupted
for attrib, val in iteritems(asides):
setattr(self, attrib, val)
raise
return restores + [(self, asides)]
def save(self, fname_or_handle, separately=None, sep_limit=10 * 1024**2, ignore=frozenset(), pickle_protocol=2):
"""Save the object to file.
Parameters
----------
fname_or_handle : str or file-like
Path to output file or already opened file-like object. If the object is a file handle,
no special array handling will be performed, all attributes will be saved to the same file.
separately : list of str or None, optional
If None - automatically detect large numpy/scipy.sparse arrays in the object being stored, and store
them into separate files. This avoids pickle memory errors and allows mmap'ing large arrays
back on load efficiently.
If list of str - this attributes will be stored in separate files, the automatic check
is not performed in this case.
sep_limit : int
Limit for automatic separation.
ignore : frozenset of str
Attributes that shouldn't be serialize/store.
pickle_protocol : int
Protocol number for pickle.
See Also
--------
:meth:`~gensim.utils.SaveLoad.load`
"""
try:
_pickle.dump(self, fname_or_handle, protocol=pickle_protocol)
logger.info("saved %s object", self.__class__.__name__)
except TypeError: # `fname_or_handle` does not have write attribute
self._smart_save(fname_or_handle, separately, sep_limit, ignore, pickle_protocol=pickle_protocol)
def identity(p):
"""Identity fnc, for flows that don't accept lambda (pickling etc).
Parameters
----------
p : object
Input parameter.
Returns
-------
object
Same as `p`.
"""
return p
def get_max_id(corpus):
"""Get the highest feature id that appears in the corpus.
Parameters
----------
corpus : iterable of iterable of (int, int)
Collection of texts in BoW format.
Returns
------
int
Highest feature id.
Notes
-----
For empty `corpus` return -1.
"""
maxid = -1
for document in corpus:
maxid = max(maxid, max([-1] + [fieldid for fieldid, _ in document])) # [-1] to avoid exceptions from max(empty)
return maxid
class FakeDict(object):
"""Objects of this class act as dictionaries that map integer->str(integer), for a specified
range of integers <0, num_terms).
This is meant to avoid allocating real dictionaries when `num_terms` is huge, which is a waste of memory.
"""
def __init__(self, num_terms):
"""
Parameters
----------
num_terms : int
Number of terms.
"""
self.num_terms = num_terms
def __str__(self):
return "FakeDict(num_terms=%s)" % self.num_terms
def __getitem__(self, val):
if 0 <= val < self.num_terms:
return str(val)
raise ValueError("internal id out of bounds (%s, expected <0..%s))" % (val, self.num_terms))
def iteritems(self):
"""Iterate over all keys and values.
Yields
------
(int, str)
Pair of (id, token).
"""
for i in xrange(self.num_terms):
yield i, str(i)
def keys(self):
"""Override the `dict.keys()`, which is used to determine the maximum internal id of a corpus,
i.e. the vocabulary dimensionality.
Returns
-------
list of int
Highest id, packed in list.
Warnings
--------
To avoid materializing the whole `range(0, self.num_terms)`,
this returns the highest id = `[self.num_terms - 1]` only.
"""
return [self.num_terms - 1]
def __len__(self):
return self.num_terms
def get(self, val, default=None):
if 0 <= val < self.num_terms:
return str(val)
return default
def dict_from_corpus(corpus):
"""Scan corpus for all word ids that appear in it, then construct a mapping
which maps each `word_id` -> `str(word_id)`.
Parameters
----------
corpus : iterable of iterable of (int, int)
Collection of texts in BoW format.
Returns
------
id2word : :class:`~gensim.utils.FakeDict`
"Fake" mapping which maps each `word_id` -> `str(word_id)`.
Warnings
--------
This function is used whenever *words* need to be displayed (as opposed to just their ids)
but no `word_id` -> `word` mapping was provided. The resulting mapping only covers words actually
used in the corpus, up to the highest `word_id` found.
"""
num_terms = 1 + get_max_id(corpus)
id2word = FakeDict(num_terms)
return id2word
def is_corpus(obj):
"""Check whether `obj` is a corpus.
Parameters
----------
obj : object
Something `iterable of iterable` that contains (int, int).
Return
------
(bool, object)
Pair of (is_corpus, `obj`), is_corpus True if `obj` is corpus.
Warnings
--------
An "empty" corpus (empty input sequence) is ambiguous, so in this case
the result is forcefully defined as (False, `obj`).
"""
try:
if 'Corpus' in obj.__class__.__name__: # the most common case, quick hack
return True, obj
except Exception:
pass
try:
if hasattr(obj, 'next') or hasattr(obj, '__next__'):
# the input is an iterator object, meaning once we call next()
# that element could be gone forever. we must be careful to put
# whatever we retrieve back again
doc1 = next(obj)
obj = itertools.chain([doc1], obj)
else:
doc1 = next(iter(obj)) # empty corpus is resolved to False here
if len(doc1) == 0: # sparse documents must have a __len__ function (list, tuple...)
return True, obj # the first document is empty=>assume this is a corpus
# if obj is a 1D numpy array(scalars) instead of 2-tuples, it resolves to False here
id1, val1 = next(iter(doc1))
id1, val1 = int(id1), float(val1) # must be a 2-tuple (integer, float)
except Exception:
return False, obj
return True, obj
def get_my_ip():
"""Try to obtain our external ip (from the Pyro4 nameserver's point of view)
Returns
-------
str
IP address.
Warnings
--------
This tries to sidestep the issue of bogus `/etc/hosts` entries and other local misconfiguration,
which often mess up hostname resolution.
If all else fails, fall back to simple `socket.gethostbyname()` lookup.
"""
import socket
try:
from Pyro4.naming import locateNS
# we know the nameserver must exist, so use it as our anchor point
ns = locateNS()
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
s.connect((ns._pyroUri.host, ns._pyroUri.port))
result, port = s.getsockname()
except Exception:
try:
# see what ifconfig says about our default interface
import commands
result = commands.getoutput("ifconfig").split("\n")[1].split()[1][5:]
if len(result.split('.')) != 4:
raise Exception()
except Exception:
# give up, leave the resolution to gethostbyname
result = socket.gethostbyname(socket.gethostname())
return result
class RepeatCorpus(SaveLoad):
"""Wrap a `corpus` as another corpus of length `reps`. This is achieved by repeating documents from `corpus`
over and over again, until the requested length `len(result) == reps` is reached.
Repetition is done on-the-fly=efficiently, via `itertools`.
Examples
--------
>>> from gensim.utils import RepeatCorpus
>>>
>>> corpus = [[(1, 2)], []] # 2 documents
>>> list(RepeatCorpus(corpus, 5)) # repeat 2.5 times to get 5 documents
[[(1, 2)], [], [(1, 2)], [], [(1, 2)]]
"""
def __init__(self, corpus, reps):
"""
Parameters
----------
corpus : iterable of iterable of (int, int)
Input corpus.
reps : int
Number of repeats for documents from corpus.
"""
self.corpus = corpus
self.reps = reps
def __iter__(self):
return itertools.islice(itertools.cycle(self.corpus), self.reps)
class RepeatCorpusNTimes(SaveLoad):
"""Wrap a `corpus` and repeat it `n` times.
Examples
--------
>>> from gensim.utils import RepeatCorpusNTimes
>>>
>>> corpus = [[(1, 0.5)], []]
>>> list(RepeatCorpusNTimes(corpus, 3)) # repeat 3 times
[[(1, 0.5)], [], [(1, 0.5)], [], [(1, 0.5)], []]
"""
def __init__(self, corpus, n):
"""
Parameters
----------
corpus : iterable of iterable of (int, int)
Input corpus.
n : int
Number of repeats for corpus.
"""
self.corpus = corpus
self.n = n
def __iter__(self):
for _ in xrange(self.n):
for document in self.corpus:
yield document
class ClippedCorpus(SaveLoad):
"""Wrap a `corpus` and return `max_doc` element from it"""
def __init__(self, corpus, max_docs=None):
"""
Parameters
----------
corpus : iterable of iterable of (int, int)
Input corpus.
max_docs : int
Maximal number of documents in result corpus.
Warnings
--------
Any documents after `max_docs` are ignored. This effectively limits the length of the returned corpus
to <= `max_docs`. Set `max_docs=None` for "no limit", effectively wrapping the entire input corpus.
"""
self.corpus = corpus
self.max_docs = max_docs
def __iter__(self):
return itertools.islice(self.corpus, self.max_docs)
def __len__(self):
return min(self.max_docs, len(self.corpus))