QGIS/python/plugins/processing/algs/qgis/help/selectbyattribute.rst
Victor Olaya 15e923820f [processing] added help files for algs in qgis group
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2014-06-08 20:00:03 +02:00

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SELECT BY ATTRIBUTE
===================
Description
-----------
With this algorithm you can make a subset of a layer according to specific parameters referring to an attribute table field.
For example you may want to select features of a polygons layer that have an area smaller than a specific value.
Be aware that the algorithm is case-sensitive ("qgis" is different from "Qgis" and from "QGIS")!
Parameters
----------
- ``Input Layer[Vector]``: layer in input (can be a points, lines or a polygons layer)
- ``Selection attribute[TableField]``: field of the attribute table on which perform the selection
- ``Comparison[Selection]``: type of comparison operator
- ``Value[String]``: value on which perform the comparison
Outputs
-------
- ``Output[Vector]``: the algorithm doesn't create a new layer, it just made a selection of the input layer
See also
---------
Console usage
-------------
::
processing.runalg('qgis:selectbyattribute', layername, attribute, comparison, comparisonvalue)
Available options for selection parameters:
comparison(Comparison)
0 - ==
1 - !=
2 - >
3 - >=
4 - <
5 - <=
6 - begins with
7 - contains