QGIS/python/plugins/processing/algs/qgis/help/zonalstatistics.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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ZONAL STATISTICS
================
Description
-----------
This algorithm calculates some statistics values for pixels of input raster
inside certain zones, defined as polygon layer.
Following values calculated for each zone:
* minimum
* maximum
* sum
* count
* mean
* standard deviation
* number of unique values
* range
* variance
All results stored in output vector layer in columns with user-defined prefix.
Parameters
----------
- ``Raster layer``: The raster layer to use.
- ``Raster band``: The band number.
- ``Vector layer containing zones``: The vector layer with zones.
- ``Output column prefix``: User-defined prefix for output columns.
- ``Load whole raster in memory``: Determines if raster band will be loaded in
memory or readed by chunks. Useful only when disk IO or raster scanning
inefficiencies are your limiting factor.
Outputs
-------
- ``Output layer``: The resulting layer with new columns added.
See also
--------
Console usage
-------------
::
processing.runalg("qgis:zonalstatistics", input_raster, band_number, input_vector, column_prefix, load_flag, output_layer)