source: orange/docs/widgets/rst/data/file.rst @ 11789:4a79384c2b1e

Revision 11789:4a79384c2b1e, 2.9 KB checked in by blaz <blaz.zupan@…>, 4 months ago (diff)

Minor changes in documentation for File widget.

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