source: orange/docs/widgets/rst/visualize/attributestatistics.rst @ 11359:8d54e79aa135

Revision 11359:8d54e79aa135, 2.0 KB checked in by Ales Erjavec <ales.erjavec@…>, 14 months ago (diff)

Cleanup of 'Widget catalog' documentation.

Fixed rst text formating, replaced dead hardcoded reference links (now using
:ref:), etc.

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1.. _Attribute Statistics:
2
3Attribute Statistics
4====================
5
6.. image:: ../icons/AttributeStatistics.png
7
8Shows basic distribution of attribute values.
9
10Signals
11-------
12
13Inputs:
14   - Examples (ExampleTable)
15      Input data set.
16
17
18Outputs:
19   - (None)
20
21
22Description
23-----------
24
25Attribute Statistics shows distributions of attribute values. It is a good
26practice to check any new data with this widget, to quickly discover any
27anomalies, such as duplicated values (e.g. gray and grey), outliers, and
28similar.
29
30.. image:: images/AttributeStatistics-Cont.png
31   :alt: Attribute Statistics for continuous features
32
33For continuous attributes, the widget shows the minimal and maximal value.
34In case of Iris' attribute "petal length" (figure on the left), these are
351.00 and 6.90. In between are the 25'th percentile, the median and the 75%,
36which are 1.60, 4.35 and 5.10, respectively. The mean and standard deviation
37are printed in red (3.76 and 1.76) and also represented with the vertical line.
38At the bottom left corner there is also information on the sample size (there
39are 150 examples in the Iris data set, without any missing values) and the
40number of distinct values that this attribute takes.
41
42.. image:: images/AttributeStatistics-Disc.png
43
44For discrete attributes, the bars represent the number of examples with each
45particular attribute value. The picture shows the number of different animal
46types in the Zoo data set: there are 41 mammals, 13 fish and so forth.
47
48
49For both kinds of attributes, the graph can be saved by clicking the
50:obj:`Save Graph` button.
51
52Examples
53--------
54
55Attribute Statistics is most commonly used immediately after the :ref:`File`
56widget to observe statistical properties of the data set. It is also useful for
57finding the properties of a specific data set, for instance a group of
58examples manually defined in another widget, such as scatter plot or examples
59belonging to some cluster or a classification tree node, as shown in the
60schema below.
61
62.. image:: images/AttributeStatistics-Schema.png
63   :alt: Attribute Statistics Example schema
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