Add segment-wiki script

docs/src/apiref.rst

@@ -79,6 +79,7 @@ Modules:
     scripts/make_wiki_online_lemma
     scripts/make_wiki_online_nodebug
     scripts/word2vec2tensor
+    scripts/segment_wiki
     parsing/porter
     parsing/preprocessing
     summarization/bm25

docs/src/scripts/segment_wiki.rst

@@ -0,0 +1,9 @@
+:mod:`scripts.segment_wiki` -- Convert wikipedia dump to plain text format
+==========================================================================
+
+.. automodule:: gensim.scripts.segment_wiki
+    :synopsis: Convert wikipedia dump to plain text format.
+    :members:
+    :inherited-members:
+    :undoc-members:
+    :show-inheritance:

gensim/scripts/segment_wiki.py

@@ -0,0 +1,246 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+#
+# Author: Jayant Jain <jayant@rare-technologies.com>
+# Copyright (C) 2016 RaRe Technologies
+
+"""
+Construct a corpus from a Wikipedia (or other MediaWiki-based) database dump and extract sections of pages from it
+
+If you have the `pattern` package installed, this module will use a fancy
+lemmatization to get a lemma of each token (instead of plain alphabetic
+tokenizer). The package is available at https://github.com/clips/pattern .
+
+"""
+
+import argparse
+import json
+import logging
+import multiprocessing
+import re
+import sys
+from xml.etree import cElementTree
+
+from gensim.corpora.wikicorpus import ARTICLE_MIN_WORDS, IGNORED_NAMESPACES, WikiCorpus, \
+    filter_wiki, get_namespace, tokenize, utils
+from smart_open import smart_open
+
+
+logger = logging.getLogger(__name__)
+
+
+def segment_all_articles(file_path):
+    """Extract article titles and sections from a MediaWiki bz2 database dump.
+
+    Parameters
+    ----------
+    file_path : str
+        Path to mediawiki dump, typical filename is <LANG>wiki-<YYYYMMDD>-pages-articles.xml.bz2
+        or <LANG>wiki-latest-pages-articles.xml.bz2.
+
+    Yields
+    ------
+    tuple(str, list of tuple(str, str))
+        Structure contains (title, [(section_heading, section_content), ...]).
+
+    """
+    with smart_open(file_path, 'rb') as xml_fileobj:
+        wiki_sections_corpus = WikiSectionsCorpus(xml_fileobj)
+        wiki_sections_corpus.metadata = True
+        wiki_sections_text = wiki_sections_corpus.get_texts_with_sections()
+        for article_title, article_sections in wiki_sections_text:
+            yield article_title, article_sections
+
+
+def segment_and_print_all_articles(file_path, output_file):
+    """Write article title and sections to output_file,
+    tab-separated article_title<tab>section_heading<tab>section_content<tab>section_heading<tab>section_content.
+
+    Parameters
+    ----------
+    file_path : str
+        Path to mediawiki dump, typical filename is <LANG>wiki-<YYYYMMDD>-pages-articles.xml.bz2
+        or <LANG>wiki-latest-pages-articles.xml.bz2.
+
+    output_file : str
+        Path to output file.
+
+    """
+    with smart_open(output_file, 'wb') as outfile:
+        for idx, (article_title, article_sections) in enumerate(segment_all_articles(file_path)):
+            printed_components = [json.dumps(article_title)]
+            for section_heading, section_content in article_sections:
+                printed_components.append(json.dumps(section_heading))
+                printed_components.append(json.dumps(section_content))
+            if (idx + 1) % 100000 == 0:
+                logger.info("Processed #%d articles", idx + 1)
+            outfile.write(u"\t".join(printed_components).encode('utf-8') + "\n")
+
+
+def extract_page_xmls(f):
+    """Extract pages from a MediaWiki database dump.
+
+    Parameters
+    ----------
+    f : file
+        File descriptor of MediaWiki dump.
+
+    Yields
+    ------
+    str
+        XML strings for page tags.
+
+    """
+    elems = (elem for _, elem in cElementTree.iterparse(f, events=("end",)))
+
+    elem = next(elems)
+    namespace = get_namespace(elem.tag)
+    ns_mapping = {"ns": namespace}
+    page_tag = "{%(ns)s}page" % ns_mapping
+
+    for elem in elems:
+        if elem.tag == page_tag:
+            yield cElementTree.tostring(elem)
+            # Prune the element tree, as per
+            # http://www.ibm.com/developerworks/xml/library/x-hiperfparse/
+            # except that we don't need to prune backlinks from the parent
+            # because we don't use LXML.
+            # We do this only for <page>s, since we need to inspect the
+            # ./revision/text element. The pages comprise the bulk of the
+            # file, so in practice we prune away enough.
+            elem.clear()
+
+
+def segment(page_xml):
+    """Parse the content inside a page tag
+
+    Parameters
+    ----------
+    page_xml : str
+        Content from page tag.
+
+    Returns
+    -------
+    tuple(str, list of tuple(str, str))
+        Structure contains (title, [(section_heading, section_content)]).
+
+    """
+    elem = cElementTree.fromstring(page_xml)
+    filter_namespaces = ('0',)
+    namespace = get_namespace(elem.tag)
+    ns_mapping = {"ns": namespace}
+    text_path = "./{%(ns)s}revision/{%(ns)s}text" % ns_mapping
+    title_path = "./{%(ns)s}title" % ns_mapping
+    ns_path = "./{%(ns)s}ns" % ns_mapping
+    lead_section_heading = "Introduction"
+    top_level_heading_regex = r"\n==[^=].*[^=]==\n"
+    top_level_heading_regex_capture = r"\n==([^=].*[^=])==\n"
+
+    title = elem.find(title_path).text
+    text = elem.find(text_path).text
+    ns = elem.find(ns_path).text
+    if ns not in filter_namespaces:
+        text = None
+
+    if text is not None:
+        section_contents = re.split(top_level_heading_regex, text)
+        section_headings = [lead_section_heading] + re.findall(top_level_heading_regex_capture, text)
+        assert len(section_contents) == len(section_headings)
+    else:
+        section_contents = []
+        section_headings = []
+
+    section_contents = [filter_wiki(section_content) for section_content in section_contents]
+    sections = list(zip(section_headings, section_contents))
+    return title, sections
+
+
+class WikiSectionsCorpus(WikiCorpus):
+    """Treat a wikipedia articles dump (<LANG>wiki-<YYYYMMDD>-pages-articles.xml.bz2
+    or <LANG>wiki-latest-pages-articles.xml.bz2) as a (read-only) corpus.
+
+    The documents are extracted on-the-fly, so that the whole (massive) dump can stay compressed on disk.
+
+    """
+    def __init__(self, fileobj, processes=None, lemmatize=utils.has_pattern(), filter_namespaces=('0',)):
+        """Initialize the corpus. Unless a dictionary is provided, this scans the
+        corpus once, to determine its vocabulary.
+
+        . You can override
+        this automatic logic by forcing the `lemmatize` parameter explicitly.
+
+        Parameters
+        ----------
+        fileobj : file
+            File descriptor of MediaWiki dump.
+        processes : int
+            Number of processes, max(1, multiprocessing.cpu_count() - 1) if None.
+        lemmatize : bool
+            If `pattern` package is installed, use fancier shallow parsing to get token lemmas.
+            Otherwise, use simple regexp tokenization.
+        filter_namespaces : tuple(int)
+            Enumeration of namespaces that will be ignored.
+
+        """
+        self.fileobj = fileobj
+        self.filter_namespaces = filter_namespaces
+        self.metadata = False
+        if processes is None:
+            processes = max(1, multiprocessing.cpu_count() - 1)
+        self.processes = processes
+        self.lemmatize = lemmatize
+
+    def get_texts_with_sections(self):
+        """Iterate over the dump, returning titles and text versions of all sections of articles.
+
+        Notes
+        -----
+        Only articles of sufficient length are returned (short articles & redirects
+        etc are ignored).
+
+        Note that this iterates over the **texts**; if you want vectors, just use
+        the standard corpus interface instead of this function::
+
+        >>> for vec in wiki_corpus:
+        >>>     print(vec)
+
+        Yields
+        ------
+        tuple(str, list of tuple(str, str))
+            Structure contains (title, [(section_heading, section_content), ...]).
+
+        """
+        articles = 0
+        page_xmls = extract_page_xmls(self.fileobj)
+        pool = multiprocessing.Pool(self.processes)
+        # process the corpus in smaller chunks of docs, because multiprocessing.Pool
+        # is dumb and would load the entire input into RAM at once...
+        for group in utils.chunkize(page_xmls, chunksize=10 * self.processes, maxsize=1):
+            for article_title, sections in pool.imap(segment, group):  # chunksize=10):
+                # article redirects and short stubs are pruned here
+                num_total_tokens = 0
+                for section_title, section_content in sections:
+                    if self.lemmatize:
+                        num_total_tokens += len(utils.lemmatize(section_content))
+                    else:
+                        num_total_tokens += len(tokenize(section_content))
+                if num_total_tokens < ARTICLE_MIN_WORDS or \
+                        any(article_title.startswith(ignore + ':') for ignore in IGNORED_NAMESPACES):
+                    continue
+                articles += 1
+                yield (article_title, sections)
+        pool.terminate()
+        self.length = articles  # cache corpus length
+
+
+if __name__ == "__main__":
+    logging.basicConfig(format='%(asctime)s : %(processName)s : %(levelname)s : %(message)s', level=logging.INFO)
+    logger.info("running %s", " ".join(sys.argv))
+
+    parser = argparse.ArgumentParser(formatter_class=argparse.RawTextHelpFormatter, description=globals()['__doc__'])
+    parser.add_argument('-f', '--file', help='Path to mediawiki database dump', required=True)
+    parser.add_argument('-o', '--output', help='Path to output file', required=True)
+    args = parser.parse_args()
+    segment_and_print_all_articles(args.file, args.output)
+
+    logger.info("finished running %s", sys.argv[0])