1
from qgis.analysis import QgsRasterCalculator, QgsRasterCalculatorEntry import processing
from osgeo import osr, gdal from gdalconst import *

dataset1 = gdal.Open(input1, GA_Update) band1 = dataset1.GetRasterBand(1) dataset1.SetProjection( srs.ExportToWkt() ) dataset1 = None

layer1=QgsRasterLayer(dataset1,'test1')
#layer1.setCrs( QgsCoordinateReferenceSystem(3003, QgsCoordinateReferenceSystem.EpsgCrsId) )

print('load first layer')

input2='D:\\ascii2grids\\dati_ascii\\PR_2018091500UTCplus1.txt'

dataset2 = gdal.Open(input2, GA_Update) band2 = dataset2.GetRasterBand(1) dataset2.SetProjection( srs.ExportToWkt() ) dataset2 = None

layer2=QgsRasterLayer(dataset2,'test2')

print('load II layer')

exp = "%s - %s" % (layer1,layer2)

output='C:\\Users\\assis\\test.tif'

entries=[layer1,layer2]

calc = QgsRasterCalculator(exp,
                    output,
                    'GTiff',
                    layer1.extent,
                    QgsCoordinateReferenceSystem("EPSG:3003"),
                    layer1.width,
                    layer1.height,
                    entries
                    )

res = calc.processCalculation(feedback) if res == QgsRasterCalculator.ParserError:
    raise QgsProcessingException(self.tr("Error parsing formula"))

This pyqgis script give me the following error:

Traceback (most recent call last):   File "C:\OSGEO4~1\apps\Python37\lib\code.py", line 90, in runcode
    exec(code, self.locals)   File "<input>", line 1, in <module>   File "<string>", line 57, in <module> TypeError: QgsRasterCalculator(): arguments did not match any overloaded call:   overload 1: argument 4 has unexpected type 'builtin_function_or_method'   overload 2: argument 4 has unexpected type 'builtin_function_or_method'   overload 3: argument 1 has unexpected type 'str'

I do not understand the error. Perhaps the CRS definition in the QgsRasterCalculator function. Unfortunately I do not find any example of how to define CRS

3

You're specifying the function instead of calling it. I.e.

layer1.extent

should be:

layer1.extent()

Do this with width and height:

calc = QgsRasterCalculator(exp,
                        output,
                        'GTiff',
                        layer1.extent(),
                        QgsCoordinateReferenceSystem("EPSG:3003"),
                        layer1.width(),
                        layer1.height(),
                        entries
                        )
  • 1
    a small addition: PyQGIS always(?) uses methods instead of properties. I think this is because of sip, which is the way/interface PyQIS calls from C++ libraries. – Andreas Müller Jun 4 at 10:37

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