Can not run grass:r.to.vect in Qgis console

Question

I call using processing.alghelp("grass:r.to.vect")

I looked input:

 <ParameterRaster>
feature <ParameterSelection>
-s <ParameterBoolean>
GRASS_REGION_PARAMETER <ParameterExtent>
GRASS_OUTPUT_TYPE_PARAMETER <ParameterSelection>
output <OutputVector>


feature(Feature type)
    0 - line
    1 - point
    2 - area
GRASS_OUTPUT_TYPE_PARAMETER(v.out.ogr output type)
    0 - auto
    1 - point
    2 - line
    3 - area

then I try to do , processing.runalg("grass:r.to.vect" , iface.activeLayer,2, True, None,3,r"C:\Users\user2\Desktop\1\temp\drfsg\zhopa.shp")") but it returns an error, what I did wrong? the project is only one raster layer

You should use correct path-notation in strings: r"C:\Users\user2\Desktop\1\temp\drfsg" or "C:/Users/user2/Desktop/1/temp/drfsg" or "C:\Users\user2\Desktop\1\temp\drfsg" Don't know if thats the issue.. — Andreas Müller, Feb 09 '17 at 09:42
that is not the way, it gives another error , 'int' object has no attribute 'split' — frontend33, Feb 09 '17 at 09:44
I think your GRASS_REGION_PARAMETER needs no int (your value is 2) but should be a string like it was used here: http://gis.stackexchange.com/questions/75666/how-to-call-processing-toolbox-in-qgis-python-console — Andreas Müller, Feb 09 '17 at 09:58
processing.runalg("grass:r.to.vect" , iface.activeLayer,2, True, None,3,r"C:\Users\user2\Desktop\1\temp\drfsg\zhopa.shp") writing does not issue error, but nothing happens, does not work — frontend33, Feb 09 '17 at 10:05
if the code runs without an error than it is likely a problem with the dataset used. Data values, data size, for example. So please give more information about what you trying to achieve. — Andreas Müller, Feb 09 '17 at 10:14
I have a raster, I want it to turn the console into a vector using, r.to.vect — frontend33, Feb 09 '17 at 10:21

score 1 · Accepted Answer · answered Feb 09 '17 at 10:26

1

The recent QGIS versions have implemented GRASS7 into its processing framework as default so you may need to use grass7:r.to.vect instead of grass:r.to.vect. I have also experienced issues when trying to set the GRASS_REGION_PARAMETER to blank, instead I use the extents of the input layer as that's usually what I am interested in.

So you could try the following code into the python console:

from PyQt4.QtCore import QFileInfo
import processing

# Identify raster layer
raster = iface.activeLayer()
fileName = raster.source()
fileInfo = QFileInfo(fileName)
baseName = fileInfo.baseName()
rlayer = QgsRasterLayer(fileName, baseName)

# Define the extent of the region
extent = rlayer.extent()
xmin = extent.xMinimum()
xmax = extent.xMaximum()
ymin = extent.yMinimum()
ymax = extent.yMaximum()

processing.runalg("grass7:r.to.vect",rlayer,2,True,"%f,%f,%f,%f"% (xmin, xmax, ymin, ymax),3,"C:/Users/user2/Desktop/1/temp/drfsg/zhopa.shp")

answered Feb 09 '17 at 10:26

Joseph

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thank you very much it works on both the version Qgis 12.8 and 12.2 as ))) Is it possible in this vector layer to make more transparent the fill? – frontend33 Feb 09 '17 at 10:38
@АзаматВалиев - Most welcome, glad it worked! You can make it transparent by changing its style properties by right-clicking the layer and going to Properties > Style :) – Joseph Feb 09 '17 at 10:47
and whether it is an important question, Grass gis 7 coverage of the region, select the coverage on the map instead of coordinates? – frontend33 Feb 09 '17 at 10:48
and about transparency, I'm doing a module, so that would not have to manually change namely through the console – frontend33 Feb 09 '17 at 10:49
@АзаматВалиев - You can define your own coordinates by replacing "%f,%f,%f,%f"% (xmin, xmax, ymin, ymax) with "0.0, 1.0, 2.0, 3.0" (note they are inside a string). If you want to change the transparency of the layer, there are a number of posts asked here on GIS:SE such as this one: How do I set layer transparency in QGIS 2.0 with Python? – Joseph Feb 09 '17 at 10:55
thank you very much, and the last question that worries me, is it possible process "save as" in the console? I need to save as well as in the horizontal and vertical resolution to put the 5 by 5 meters (pixel) – frontend33 Feb 09 '17 at 11:14
@АзаматВалиев - I'm guessing you asked this question? In which case, take a look at these posts which might help, you can specify the width and height: Export raster layer in python to specific folder; and QGis Save Raster as Rendered Image – Joseph Feb 09 '17 at 11:23
Yes, I tried the codes thanks, but does not go out, you can please try to maintain some sort of screen with a resolution of 5 to 5 meter, pixels through the console – frontend33 Feb 09 '17 at 11:48

Can not run grass:r.to.vect in Qgis console

1 Answers1