fcapy.context.FormalContext

class fcapy.context.FormalContext(data=None, object_names=None, attribute_names=None, **kwargs)

A class used to represent Formal Context object from FCA theory.

intention(objects)

Return maximal set of attributes which are shared by given objects

extension(attributes)

Return maximal set of objects which share given attributes

intention_i(object_indexes)

Offer the same logic as intention(…) but objects and attributes are defined by their indexes

extension_i(attribute_indexes)

Offer the same logic as extension(…) but objects and attributes are defined by their indexes

to_cxt(path=None)

Convert the FormalContext into cxt file format (save if path is given)

to_json(path=None)

Convert the FormalContext into json file format (save if path is given)

to_csv(path=None, \*\*kwargs)

Convert the FormalContext into csv file format (save if path is given)

to_pandas()

Convert the FormalContext into pandas.DataFrame object

Notes

Formal Context K = (G, M, I) - is a triplet of: 1. set of objects G (the property object_names in this class) 2. set of attributes M (the property attribute_names in this class) 3. binary relation I between G and M (i.e. “gIm holds True” means “object g has attribute m”)

(the property data in this class)

__init__(data=None, object_names=None, attribute_names=None, **kwargs)

Parameters

• data (`list of `list) – Two dimensional list of bool variables. “data[i][j] = True” represents that i-th object shares j-th attribute

• object_names (`list of `str, optional) – Names of objects (rows) of the FormalContext

• attribute_names (`list of `str, optional) – Names of attributes (columns) of the FormalContext

• **kwargs –

  description:

  `str with human readable description of the FormalContext (stored only in json file format)

Methods

__init__([data, object_names, attribute_names])	param data Two dimensional list of bool variables.
extension(attributes)	Return maximal set of objects which share given attributes
extension_i(attribute_indexes)	Return indexes of maximal set of objects which share given attribute_indexes
intention(objects)	Return maximal set of attributes which are shared by given objects
intention_i(object_indexes)	Return indexes of maximal set of attributes which are shared by given ``object_indexes`
print_data([max_n_objects, max_n_attributes])	Get the FormalContext date in the string formatted as the table
to_csv([path])	Convert the FormalContext into csv file format (save if path is given)
to_cxt([path])	Convert the FormalContext into cxt file format (save if path is given)
to_json([path])	Convert the FormalContext into json file format (save if path is given)
to_pandas()	Convert the FormalContext into pandas.DataFrame object

Attributes

attribute_names	Get of set the names of the attributes in the context
data	Get or set the data with relations between objects and attributes (`list of `list)
description	Get or set the human readable description of the context
n_attributes	Get the number of attributes in the context (i.e.
n_objects	Get the number of objects in the context (i.e.
object_names	Get of set the names of the objects in the context

property attribute_names

Get of set the names of the attributes in the context

Parameters

value (`list of `str) – The list of names for the attributes (default are “0”,”1”,…,”n_attributes-1”)

Raises

AssertionError – If the number of names in the value does not equal to the number of attributes in the context If the the elements of value are not of type str

property data

Get or set the data with relations between objects and attributes (`list of `list)

Parameters

value (`list of `list) – value[i][j] represents whether i-th object shares j-th attribute

Raises

AssertionError – If value is not a list If ``value` of type list is given (should be `list of `list) If some lists ``value[i]` and value[j] have different length (should be the same for any value[i]) If any value[i][j] is not of type `bool

property description

Get or set the human readable description of the context

JSON is the only file format to store this information. The description will be lost when saving context to .cxt or .csv

Parameters

value (`str, None) – The human readable description of the context

Raises

AssertionError – If the given value is not None and not of type `str

extension(attributes)

Return maximal set of objects which share given attributes

Parameters

attributes (`list of `str) – Names of the attributes (subset of attribute_names)

Returns

extension – Names of the maximal set of objects which share given attributes

Return type

`list of `str

extension_i(attribute_indexes)

Return indexes of maximal set of objects which share given attribute_indexes

Parameters

attribute_indexes (`list of `int) – Indexes of the attributes (from [0, n_attributes-1])

Returns

extension_indexes – Indexes of maximal set of objects which share attributes

Return type

`list of `int

intention(objects)

Return maximal set of attributes which are shared by given objects

Parameters

objects (`list of `str) – Names of the objects (subset of object_names)

Returns

intention – Names of maximal set of attributes which are shared by given objects

Return type

`list of `str

intention_i(object_indexes)

Return indexes of maximal set of attributes which are shared by given ``object_indexes`

Parameters

object_indexes (`list of `int) – Indexes of the objects (from [0, n_objects-1])

Returns

intention_i – Indexes of maximal set of attributes which are shared by objects

Return type

`list of `int

property n_attributes

Get the number of attributes in the context (i.e. len(data[0])

property n_objects

Get the number of objects in the context (i.e. len(data))

property object_names

Get of set the names of the objects in the context

Parameters

value (`list of `str) – The list of names for the objects (default are ‘0’,’1’,…,’n_objects-1’)

Raises

AssertionError – If the number of names in the value does not equal to the number of objects in the context If the the elements of value are not of type str

print_data(max_n_objects=20, max_n_attributes=10)

Get the FormalContext date in the string formatted as the table

Parameters

• max_n_objects (`int) – Maximal number of objects to print. If it is less then n_objects then print max_n_objects/2 objects from the “top” and the “bottom” of the context

• max_n_attributes (`int) – Maximal number of attributes to print. If it is less then n_attributes then print max_n_attributes/2 attributes from the “left” and the “right” part of the context

Returns

data_to_print – A string with the context data formatted as the table

Return type

`str

to_csv(path=None, **kwargs)

Convert the FormalContext into csv file format (save if path is given)

Parameters

• path (`str or None) – Path to save a context

• **kwargs –

  sep`str

  Field delimiter for the output file

  word_true`str

  A placeholder to put instead of ‘True’ for data[i][j]==True (default ‘True’)

  word_false`str

  A placeholder to put instead of ‘False’ for data[i][j]==False (default ‘False’)

Returns

context – If path is None, the string with .csv file data is returned. If path is given - return None

Return type

`str

to_cxt(path=None)

Convert the FormalContext into cxt file format (save if path is given)

Parameters

path (`str or None) – Path to save a context

Returns

context – If path is None, the string with .cxt file data is returned. If path is given - return None

Return type

`str

to_json(path=None)

Convert the FormalContext into json file format (save if path is given)

Parameters

path (`str or None) – Path to save a context

Returns

context – If path is None, the string with .json file data is returned. If path is given - return None

Return type

`str

to_pandas()

Convert the FormalContext into pandas.DataFrame object

Returns

df – The dataframe with boolean variables, object_names turned into df.index, attribute_names turned into df.columns

Return type

pandas.DataFrame