source: orange/docs/widgets/rst/data/file.rst @ 11812:3912cba8d2a6

Revision 11812:3912cba8d2a6, 3.0 KB checked in by blaz <blaz.zupan@…>, 4 months ago (diff)

Updated documentation for the Save widget.

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