source: orange/docs/widgets/rst/data/file.rst @ 11810:60ae48329b9a

Revision 11810:60ae48329b9a, 3.2 KB checked in by blaz <blaz.zupan@…>, 4 months ago (diff)

Changed style in description of signals (for new widget documentation).

Line 
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   - :obj:`Data`
20         Attribute-valued data set read from the input file.
21
22
23.. _my-reference-label:
24
25Section to cross-reference
26--------------------------
27
28This is the text of the section.
29
30It refers to the section itself, see :ref:`my-reference-label`.
31
32
33Description
34-----------
35
36File widget reads the input data file (data table with data instances)
37and sends the data set to its output channel. It maintains
38a history of most recently opened files. For convenience, the history also includes
39a directory with the sample data sets that come pre-installed with Orange.
40
41The widget reads data from simple tab-delimited or comma-separated files,
42as well as files in
43`Weka's arrf format <http://www.cs.waikato.ac.nz/~ml/weka/arff.html>`_.
44
45.. image:: images/File-stamped.png
46   :alt: File widget with loaded Iris data set
47   :align: right
48
49.. rst-class:: stamp-list
50
51   1. Browse for a data file.
52   #. Browse through previously opened data files, or load any of the sample data
53      files.
54   #. Reloads currently selected data file.
55   #. Information on loaded data set (data set size, number and types of
56      data features).
57   #. Opens a sub-window with advanced settings.
58   #. Adds a report on data set info (size, features).
59
60.. container:: clearer
61
62    .. image :: images/spacer.png
63
64Advanced Options
65----------------
66
67.. image:: images/File-Advanced-stamped.png
68   :alt: Advanced options of File widget
69   :align: right
70
71.. rst-class:: stamp-list
72
73   1. Symbol for don't care data entry.
74   #. Symbol for don't know data entry.
75   #. Settings for treatment of feature names in the feature space of Orange.
76
77.. container:: clearer
78
79    .. image :: images/spacer.png
80
81Tab-delimited data file can include user defined symbols for undefined values. The symbols for
82"don't care" and "don't know" values can be specified in the corresponding edit lines.
83The default values for "don't know" and "don't care" depend upon format. Most users will
84use tab-delimited files: keep the field empty or put a question mark in there and that's
85it. Most algorithms do not differ between don't know and don't care values, so consider
86them both to mean undefined.
87
88Orange will usually treat the attributes with the same name
89but appearing in different files as the same attribute, so a classifier which uses the
90attribute "petal length" from the first will use the attribute of the same name from
91the second. In cases when attributes from different files just accidentally bear different
92names, one can instruct Orange to either always construct new attribute or construct them when
93they differ in their domains. Use the options on dealing with new attributes
94with great care (if at all).
95
96Example
97-------
98
99Most Orange workflows would probably start with the File widget. In the schema below,
100the widget is used to read the data that is sent to both :ref:`Data Table` widget and
101to widget that displays :ref:`Attribute Statistics`.
102
103.. image:: images/File_schema.png
104   :alt: Example schema with File widget
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