Using SAGA reclassification with tabled categories in QGIS script

Question

I am using QGIS, and I would like to write a script to help processing the data.

To do so, I have to reclassify heights values from a raster. I have written the following code, where retab is the path to the file containing the reclassification rules (see later) :

##Layer1=raster


from qgis.core import *
from qgis.gui import *
from qgis.utils import iface
from PyQt4.QtCore import *
from PyQt4.QtGui import *
import os
import processing

retab = "E:\\Divers\\Qgis\\Scripts\\tab_reclass.txt"
#processing.runalg('saga:reclassifygridvalues', input, method, old, new, soperator, min, max, rnew, roperator, retab, toperator, nodataopt, nodata, otheropt, others, result)

Layerout=processing.runalg('saga:reclassifygridvalues', Layer1, 2, 0, 0, 0, 0, 0, 0, retab, 0, 0, 0, 0, 0, 0, 0)

The code gives the following error :

Error: Wrong parameter value: E:\Divers\Qgis\Scripts\tab_reclass.txt

My rules are the following :

minimum maximum new
0   0.5 1
0.5 2   2
2   1000    3

I could not find a clear example on how to use the table rules, so I guess that it is where the error comes from.

If possible, I would prefer using the rules from the script rather than from the external file.

Answer 1

The following should hopefully work:

##Layer1=raster

Layerout=processing.runalg('saga:reclassifygridvalues', Layer1, 2, 0, 0, 0, 0, 0, 0, 0, '0,0.5,1,0.5,2,2,2,1000,3', 0, 0, 0, 0, 0, None)

---

Notes:

• No output is produced as I'm assuming you're going to process it further (but you can replace runalg with runandload to see what the output looks like.

• You can avoid using a lookup table by typing the 'minimum,maximum,new' values in a string. So if you have 3 rows, you would type it continuously (e.g. 'minimum,maximum,new,minimum,maximum,new,minimum,maximum,new'.