[Qgis-developer] iteration over raster

Alexander Bruy alexander.bruy at gmail.com
Thu Feb 24 11:29:02 EST 2011


AFAIK in QGIS API there are no methods for modifying raster cells.
To learn about querying raster values look at qgsmaptoolidentify.cpp file
in QGIS source tree.

If you want not only read pixel values but modify them, look at GDAL
and NumPy.

On Thu, 24 Feb 2011 16:36:01 +0100
Andruit at gmx.de wrote:

> Hello,
> I would like to write a qgis python plugin, which modifies cell values based on the values of their surrounding neighbors.
> 
> But how can I iterate over a raster layer in order to read the value of each raster cell (and its surrounding neighbors)?
> Is there any method querying raster cell values
> 
> for i in range (1, numberofrows)
>   for j in range (1, numberofcolumns)
>      
>        value=???  #read cell value of cell[i j]
> 
> 
> Thank you very much in advance. 
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-- 
Alexander Bruy


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