source: orange/docs/widgets/rst/data/datasampler.rst @ 11778:ecd4beec2099

Revision 11778:ecd4beec2099, 1.9 KB checked in by Ales Erjavec <ales.erjavec@…>, 5 months ago (diff)

Use new SVG icons in the widget documentation.

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1.. _Data Sampler:
2
3Data Sampler
4============
5
6.. image:: ../../../../Orange/OrangeWidgets/Data/icons/DataSampler.svg
7
8Selects a subset of data instances from the input data set.
9
10Signals
11-------
12
13Inputs:
14
15
16   - Examples (ExampleTable)
17      Attribute-valued data set.
18
19
20Outputs:
21
22
23   - Sample (ExampleTable)
24      Attribute-valued data set as sampled from the input data.
25   - Remaining Examples (ExampleTable)
26      Data instances from input data set that are not included in the sampled data.
27
28
29Description
30-----------
31
32Data Sampler supports provides support for several means of
33sampling of the data from the input channel and outputs the sampled
34data set and complementary data set (with instances from the input set
35that are not included in the sampled data set). Output is set when the
36input data set is set to the widget or after :obj:`Sample Data` is
37pressed.
38
39.. image:: images/DataSampler.png
40   :alt: Data Sampler
41
42Sampling may be stratified: if input data contains a class,
43sampling will try to match its class distribution in the output data
44sets.
45
46Several types of sampling are supported. :obj:`Random
47sampling` can draw a
48fixed number of instances or create a data set with a size set as
49a proportion of instances from the input data set. In repeated
50sampling, an data instance may be included in a sampled data several
51times (like in bootstrap).
52
53:obj:`Cross validation`,
54:obj:`Leave-one-out` or sampling that creates
55:obj:`Multiple subsets` of preset sample sizes relative to the input data set
56(like random sampling) all create several data samples. Which one is
57send to the output is determined by the data set index in :obj:`Fold/Group`
58(indices start with 1).
59
60Examples
61--------
62
63Schema where we have sampled 10 data instances from Iris data set
64and presented this selection in Scatterplot widget is shown
65below.
66
67.. image:: images/DataSampler-Example-S.gif
68   :alt: Schema with Data Sampler
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