Corpus in SVMlight format.
Corpus in SVMlight format.
Quoting http://svmlight.joachims.org/: The input file contains the training examples. The first lines may contain comments and are ignored if they start with #. Each of the following lines represents one training example and is of the following format:
<line> .=. <target> <feature>:<value> <feature>:<value> ... <feature>:<value> # <info>
<target> .=. +1 | -1 | 0 | <float>
<feature> .=. <integer> | "qid"
<value> .=. <float>
<info> .=. <string>
The “qid” feature (used for SVMlight ranking), if present, is ignored.
Although not mentioned in the specification above, SVMlight also expect its feature ids to be 1-based (counting starts at 1). We convert features to 0-base internally by decrementing all ids when loading a SVMlight input file, and increment them again when saving as SVMlight.
Initialize the corpus from a file.
Although vector labels (~SVM target class) are not used in gensim in any way, they are parsed and stored in self.labels for convenience. Set store_labels=False to skip storing these labels (e.g. if there are too many vectors to store the self.labels array in memory).
Output the document in SVMlight format, as a string. Inverse function to line2doc.
Return the document stored at file position offset.
Create a document from a single line (string) in SVMlight format
Load a previously saved object from file (also see save).
If the object was saved with large arrays stored separately, you can load these arrays via mmap (shared memory) using mmap=’r’. Default: don’t use mmap, load large arrays as normal objects.
Save a corpus in the SVMlight format.
The SVMlight <target> class tag is taken from the labels array, or set to 0 for all documents if labels is not supplied.
This function is automatically called by SvmLightCorpus.serialize; don’t call it directly, call serialize instead.
Iterate through the document stream corpus, saving the documents to fname and recording byte offset of each document. Save the resulting index structure to file index_fname (or fname.index is not set).
This relies on the underlying corpus class serializer providing (in addition to standard iteration):
each saved document,
the docbyoffset(offset) method, which returns a document positioned at offset bytes within the persistent storage (file).
Example:
>>> MmCorpus.serialize('test.mm', corpus)
>>> mm = MmCorpus('test.mm') # `mm` document stream now has random access
>>> print(mm[42]) # retrieve document no. 42, etc.