source: orange/docs/reference/rst/Orange.data.preprocess.rst @ 10542:7dde0640e266

Revision 10542:7dde0640e266, 2.5 KB checked in by anzeh <anze.staric@…>, 2 years ago (diff)

Moved preprocess from Orange to Orange.data.

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1##############################
2Preprocessing (``preprocess``)
3##############################
4
5.. automodule:: Orange.data.preprocess
6
7.. autoclass:: DiscretizeEntropy(method=Orange.feature.discretization.Entropy())
8
9.. autoclass:: RemoveContinuous
10
11.. autoclass:: Continuize
12
13.. autoclass:: RemoveDiscrete
14
15.. autoclass:: Impute
16
17.. autoclass:: FeatureSelection(measure=Orange.feature.scoring.Relief(), filter=None, limit=10)
18
19.. autofunction:: bestP
20
21.. autofunction:: bestN
22
23.. autofunction:: selectNRandom
24
25.. autofunction:: selectPRandom
26
27.. autoclass:: RFE
28
29.. autoclass:: Sample
30
31.. autoclass:: PreprocessorList
32
33.. class:: RemoveUnusedValues(variable, data, remove_one_valued=False)
34
35    Removes unused values and reduces the variable, if a variable
36    declares values that do not appear in the data.
37
38    :param variable: :obj:`~Orange.feature.Descriptor`
39    :param data: :obj:`~Orange.data.Table`
40    :param remove_one_valued: Decides whether to remove or to retain
41        the attributes with only one value defined (default: False).
42
43    Example:
44
45    .. literalinclude:: code/unusedValues.py
46
47    There are four possible outcomes:
48
49    1. The variable does not have any used values in the data - value
50    of this variable is undefined for all examples. The variable is
51    thus useless and the class returns None.
52
53    2. The variable has only one used value (or, possibly, only one
54    value at all). Such a variable is in fact useless, and can
55    probably be removed without harm. Nevertheless, its fate is
56    decided by the flag remove_one_valued which is False by default,
57    so such variables are retained unless explicitly specified
58    otherwise.
59
60    3. All variable's values occur in the data (and the variable has more
61    than one value; otherwise the above case applies). The original variable
62    is returned.
63
64    4. There are some unused values. A new variable is constructed and the
65    unused values are omitted. The value of the new variable is computed
66    automatically from the value of the original variable
67    :class:`~Orange.classification.lookup.ClassifierByLookupTable` is used
68    for mapping.
69
70    Results of example:
71
72    .. literalinclude:: code/unusedValues.res
73
74    Variables a and y are OK and are left alone. In b, value 1 is not used
75    and is removed (not in the original variable, of course; a new variable
76    is created). c is useless and is removed altogether. d is retained since
77    remove_one_valued was left at False; if we set it to True, this variable
78    would be removed as well.
79
80
81.. automodule:: Orange.data.preprocess.scaling
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