nltk.corpus.reader.api module¶
API for corpus readers.
- class nltk.corpus.reader.api.CategorizedCorpusReader[source]¶
Bases:
object
A mixin class used to aid in the implementation of corpus readers for categorized corpora. This class defines the method
categories()
, which returns a list of the categories for the corpus or for a specified set of fileids; and overridesfileids()
to take acategories
argument, restricting the set of fileids to be returned.Subclasses are expected to:
Call
__init__()
to set up the mapping.Override all view methods to accept a
categories
parameter, which can be used instead of thefileids
parameter, to select which fileids should be included in the returned view.
- __init__(kwargs)[source]¶
Initialize this mapping based on keyword arguments, as follows:
cat_pattern: A regular expression pattern used to find the category for each file identifier. The pattern will be applied to each file identifier, and the first matching group will be used as the category label for that file.
cat_map: A dictionary, mapping from file identifiers to category labels.
cat_file: The name of a file that contains the mapping from file identifiers to categories. The argument
cat_delimiter
can be used to specify a delimiter.
The corresponding argument will be deleted from
kwargs
. If more than one argument is specified, an exception will be raised.
- categories(fileids=None)[source]¶
Return a list of the categories that are defined for this corpus, or for the file(s) if it is given.
- class nltk.corpus.reader.api.CorpusReader[source]¶
Bases:
object
A base class for “corpus reader” classes, each of which can be used to read a specific corpus format. Each individual corpus reader instance is used to read a specific corpus, consisting of one or more files under a common root directory. Each file is identified by its
file identifier
, which is the relative path to the file from the root directory.A separate subclass is defined for each corpus format. These subclasses define one or more methods that provide ‘views’ on the corpus contents, such as
words()
(for a list of words) andparsed_sents()
(for a list of parsed sentences). Called with no arguments, these methods will return the contents of the entire corpus. For most corpora, these methods define one or more selection arguments, such asfileids
orcategories
, which can be used to select which portion of the corpus should be returned.- __init__(root, fileids, encoding='utf8', tagset=None)[source]¶
- Parameters:
root (PathPointer or str) – A path pointer identifying the root directory for this corpus. If a string is specified, then it will be converted to a
PathPointer
automatically.fileids – A list of the files that make up this corpus. This list can either be specified explicitly, as a list of strings; or implicitly, as a regular expression over file paths. The absolute path for each file will be constructed by joining the reader’s root to each file name.
encoding –
The default unicode encoding for the files that make up the corpus. The value of
encoding
can be any of the following:A string:
encoding
is the encoding name for all files.A dictionary:
encoding[file_id]
is the encoding name for the file whose identifier isfile_id
. Iffile_id
is not inencoding
, then the file contents will be processed using non-unicode byte strings.A list:
encoding
should be a list of(regexp, encoding)
tuples. The encoding for a file whose identifier isfile_id
will be theencoding
value for the first tuple whoseregexp
matches thefile_id
. If no tuple’sregexp
matches thefile_id
, the file contents will be processed using non-unicode byte strings.None: the file contents of all files will be processed using non-unicode byte strings.
tagset – The name of the tagset used by this corpus, to be used for normalizing or converting the POS tags returned by the
tagged_...()
methods.
- abspath(fileid)[source]¶
Return the absolute path for the given file.
- Parameters:
fileid (str) – The file identifier for the file whose path should be returned.
- Return type:
- abspaths(fileids=None, include_encoding=False, include_fileid=False)[source]¶
Return a list of the absolute paths for all fileids in this corpus; or for the given list of fileids, if specified.
- Parameters:
fileids (None or str or list) – Specifies the set of fileids for which paths should be returned. Can be None, for all fileids; a list of file identifiers, for a specified set of fileids; or a single file identifier, for a single file. Note that the return value is always a list of paths, even if
fileids
is a single file identifier.include_encoding – If true, then return a list of
(path_pointer, encoding)
tuples.
- Return type:
list(PathPointer)
- encoding(file)[source]¶
Return the unicode encoding for the given corpus file, if known. If the encoding is unknown, or if the given file should be processed using byte strings (str), then return None.
- ensure_loaded()[source]¶
Load this corpus (if it has not already been loaded). This is used by LazyCorpusLoader as a simple method that can be used to make sure a corpus is loaded – e.g., in case a user wants to do help(some_corpus).
- open(file)[source]¶
Return an open stream that can be used to read the given file. If the file’s encoding is not None, then the stream will automatically decode the file’s contents into unicode.
- Parameters:
file – The file identifier of the file to read.
- raw(fileids=None)[source]¶
- Parameters:
fileids – A list specifying the fileids that should be used.
- Returns:
the given file(s) as a single string.
- Return type:
str
- property root¶
The directory where this corpus is stored.
- Type:
- class nltk.corpus.reader.api.SyntaxCorpusReader[source]¶
Bases:
CorpusReader
An abstract base class for reading corpora consisting of syntactically parsed text. Subclasses should define:
__init__
, which specifies the location of the corpus and a method for detecting the sentence blocks in corpus files._read_block
, which reads a block from the input stream._word
, which takes a block and returns a list of list of words._tag
, which takes a block and returns a list of list of tagged words._parse
, which takes a block and returns a list of parsed sentences.