source: orange/orange/Orange/statistics/basic.py @ 7759:06a126b6aa4a

Revision 7759:06a126b6aa4a, 3.6 KB checked in by markotoplak, 3 years ago (diff)

Put Orange.statistics in the index.

Line 
1"""
2==========================================
3Basic Statistics for Continuous Features
4==========================================
5
6The are two simple classes for computing basic statistics
7for continuous features, such as their minimal and maximal value
8or average: :class:`Orange.statistics.basic.Variable` holds the statistics for a single variable
9and :class:`Orange.statistics.basic.Domain` behaves like a list of instances of
10the above class for all variables in the domain.
11
12.. class:: Variable
13
14    Computes and stores minimal, maximal, average and
15    standard deviation of a variable. It does not include the median or any
16    other statistics that can be computed on the fly, without remembering the
17    data; such statistics can be obtained classes from module :obj:`Orange.statistics.distribution`.
18
19    Instances of this class are seldom constructed manually; they are more often
20    returned by :obj:`Domain` described below.
21
22    .. attribute:: variable
23   
24        The variable to which the data applies.
25
26    .. attribute:: min
27
28        Minimal value encountered
29
30    .. attribute:: max
31
32        Maximal value encountered
33
34    .. attribute:: avg
35
36        Average value
37
38    .. attribute:: dev
39
40        Standard deviation
41
42    .. attribute:: n
43
44        Number of instances for which the value was defined.
45        If instances were weighted, :obj:`n` holds the sum of weights
46       
47    .. attribute:: sum
48
49        Weighted sum of values
50
51    .. attribute:: sum2
52
53        Weighted sum of squared values
54
55    ..
56        .. attribute:: holdRecomputation
57   
58            Holds recomputation of the average and standard deviation.
59
60    .. method:: add(value[, weight=1])
61   
62        Add a value to the statistics: adjust :obj:`min` and :obj:`max` if
63        necessary, increase :obj:`n` and recompute :obj:`sum`, :obj:`sum2`,
64        :obj:`avg` and :obj:`dev`.
65
66        :param value: Value to be added to the statistics
67        :type value: float
68        :param weight: Weight assigned to the value
69        :type weight: float
70
71    ..
72        .. method:: recompute()
73
74            Recompute the average and deviation.
75
76.. class:: Domain
77
78    ``statistics.basic.Domain`` behaves like an ordinary list, except that its
79    elements can also be indexed by variable names or descriptors.
80
81    .. method:: __init__(data[, weight=None])
82
83        Compute the statistics for all continuous variables in the data, and put
84        :obj:`None` to the places corresponding to variables of other types.
85
86        :param data: A table of instances
87        :type data: Orange.data.Table
88        :param weight: The id of the meta-attribute with weights
89        :type weight: `int` or none
90       
91    .. method:: purge()
92   
93        Remove the :obj:`None`'s corresponding to non-continuous features; this
94        truncates the list, so the indices do not respond to indices of
95        variables in the domain.
96   
97    part of `distributions-basic-stat.py`_ (uses monks-1.tab)
98   
99    .. literalinclude:: code/distributions-basic-stat.py
100        :lines: 1-10
101
102    Output::
103
104             feature   min   max   avg
105        sepal length 4.300 7.900 5.843
106         sepal width 2.000 4.400 3.054
107        petal length 1.000 6.900 3.759
108         petal width 0.100 2.500 1.199
109
110
111    part of `distributions-basic-stat`_ (uses iris.tab)
112   
113    .. literalinclude:: code/distributions-basic-stat.py
114        :lines: 11-
115
116    Output::
117
118        5.84333467484
119
120.. _distributions-basic-stat: code/distributions-basic-stat.py
121.. _distributions-basic-stat.py: code/distributions-basic-stat.py
122"""
123
124from Orange.core import BasicAttrStat as Variable
125from Orange.core import DomainBasicAttrStat as Domain
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