source: orange/docs/widgets/rst/data/file.rst @ 11792:22ed9e3a6f6f

Revision 11792:22ed9e3a6f6f, 2.9 KB checked in by blaz <blaz.zupan@…>, 4 months ago (diff)

First attempt to add color background to widget icons in documentation.

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1.. _File:
2
3File
4====
5
6.. image:: ../../../../Orange/OrangeWidgets/Data/icons/File.svg
7   :alt: File widget icon
8   :class: widget-category-data widget-icon
9
10Reads attribute-value data from an input file.
11   
12Signals
13-------
14
15Inputs:
16   - None
17
18Outputs:
19   - Data
20         Attribute-valued data set read from the input file.
21
22Description
23-----------
24
25File widget reads the input data file (data table with data instances)
26and sends the data set to its output channel. It maintains
27a history of most recently opened files. For convenience, the history also includes
28a directory with the sample data sets that come pre-installed with Orange.
29
30The widget reads data from simple tab-delimited or comma-separated files,
31as well as files in
32`Weka's arrf format <http://www.cs.waikato.ac.nz/~ml/weka/arff.html>`_.
33
34.. image:: images/File-stamped.png
35   :alt: File widget with loaded Iris data set
36   :align: right
37
381. Browse for a data file.
39#. Browse through previously opened data files, or load any of the sample data
40   files.
41#. Reloads currently selected data file.
42#. Information on loaded data set (data set size, number and types of
43   data features).
44#. Opens a sub-window with advanced settings.
45#. Adds a report on data set info (size, features).
46
47.. container:: clearer
48
49    .. image :: images/spacer.png
50
51Advanced Options
52----------------
53
54.. image:: images/File-Advanced-stamped.png
55   :alt: Advanced options of File widget
56   :align: right
57
581. Symbol for don't care data entry.
59#. Symbol for don't know data entry.
60#. Settings for treatment of feature names in the feature space of Orange.
61
62.. container:: clearer
63
64    .. image :: images/spacer.png
65
66Tab-delimited data file can include user defined symbols for undefined values. The symbols for
67"don't care" and "don't know" values can be specified in the corresponding edit lines.
68The default values for "don't know" and "don't care" depend upon format. Most users will
69use tab-delimited files: keep the field empty or put a question mark in there and that's
70it. Most algorithms do not differ between don't know and don't care values, so consider
71them both to mean undefined.
72
73Orange will usually treat the attributes with the same name
74but appearing in different files as the same attribute, so a classifier which uses the
75attribute "petal length" from the first will use the attribute of the same name from
76the second. In cases when attributes from different files just accidentally bear different
77names, one can instruct Orange to either always construct new attribute or construct them when
78they differ in their domains. Use the options on dealing with new attributes
79with great care (if at all).
80
81Example
82-------
83
84Most Orange workflows would probably start with the File widget. In the schema below,
85the widget is used to read the data that is sent to both :ref:`Data Table` widget and
86to widget that displays :ref:`Attribute Statistics`.
87
88.. image:: images/File_schema.png
89   :alt: Example schema with File widget
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