How to clip a raster by extent using Processing from the Python console?

Question

I want to clip a raster by extent in QGIS with the python console. Here is the description given in the documentation. You have to use the following input parameter:

• Input layer
• Nodata value (no_data)
• Clipping extent (projwin)
• Additional creation parameter (extra)
• output

The syntax is:

processing.runalg('gdalogr:cliprsterbyextent', input, no_data, projwin, extra, output)

I use the following data:

input = "C:/Users/....../inputraster.tif"

no_data= , , [I leave it empty]

projwin = 4278848, 3020676, 4297792, 3024646 [without " "]

extra = , , [I leave it empty]

output = "C:/Users/....../outputraster.asc"

I used these given examples in several variations, but I alway get a SyntaxError: invalid syntax.

Answer 1

You can get the correct syntax from the Processing | History and log after running the tool once from the toolbox:

processing.runalg("gdalogr:cliprasterbyextent",   
                  "C:/Users/anita/Geodata/qgis_sample_data/raster/SR_50M_alaska_nad.tif",
                  "",
                  "2001518.84322,3027531.34481,4007380.09563,4664339.34638",
                  "",
                  None)

This calls gdal_translate like this:

gdal_translate -of GTiff -projwin -6232946.6727 9275122.96868 6363148.43764 -735684.661767 
C:/Users/anita/Geodata/qgis_sample_data/raster/SR_50M_alaska_nad.tif "[temporary file]"