I am trying to run Zonal Stats for Block Group shape files against NLCD Percent Impervious raster. I have shapefiles for 48 contiguous states all projected to the same as the raster.
I've written this Python script to try and do each state shapefile in a loop. At a Linux command line I run the script, it prints out all the shapefile names to the console and does not an error but the Zonal Stats are never added to the shapefiles. It lists all the shapefile names in a second.
If I try running it from the QGIS Python Console it appears to run the script using
execfile() and no error or print statements are given but the Zonal Stats are also not added to the shapefiles. Does anyone know what I am doing wrong? Zonal Stats is running fine from the QGIS desktop.
I see there are a number of other topics on this subject but I haven't found a response in them that solves this issue.
import os, sys, traceback from PyQt4.QtGui import * from PyQt4.QtCore import * from qgis.core import * from qgis.utils import iface from qgis.analysis import QgsZonalStatistics def main(): try: shp_fldr = "/media/psf/Home/Documents/Projects/NLCD/blocks_albers" raster = "/media/psf/Home/Documents/Projects/data/2016/NLCD_2016_Impervious_L48_20190405.img" f_lst = os.listdir(shp_fldr) for fl in f_lst: if fl.find(".shp") > 0 and fl.find(".xml") < 0: print "start: " + fl shp_fl = os.path.join(shp_fldr,fl) #specify polygon shapefile vector polygonLayer = QgsVectorLayer(shp_fl, fl, "ogr") polygonLayer.startEditing() # usage - QgsZonalStatistics (QgsVectorLayer *polygonLayer, const QString &rasterFile, const QString &attributePrefix="", int rasterBand=1) zoneStat = QgsZonalStatistics (polygonLayer, raster, 'ipv-', 1, QgsZonalStatistics.Mean) zoneStat.calculateStatistics(None) polygonLayer.commitChanges() print "end: " + fl except: # Get the traceback object tb = sys.exc_info() tbinfo = traceback.format_tb(tb) # Concatenate information together concerning the error into a message string pymsg = "PYTHON ERRORS:\nTraceback info:\n" + tbinfo + "\nError Info:\n" + str(sys.exc_info()) # Return python error messages for use in script tool or Python Window print pymsg if __name__ == '__main__': main()