2

I'm trying to write a script in arcpy which reclassified a List of Rasters. This rasters are made by another tool before so there is already a loop. Actually I get the error 000582 and before this the script could reclassify but overwrote the rasters. In the end I like to count the pixel with the value 1 so that I create one raster with the sum of the value 1 as pixelvalue. How can I do this and what is wrong with the following script? Do I need the tool “plus” at the end?

import arcpy
import os
from arcpy import env
from arcpy.sa import *

arcpy.CheckOutExtension("Spatial")
env.overwriteOutput = True
env.workspace = r"D:\Julia_T\projekt\aufgabe3\testdatenA"
Dir = env.workspace
#folder to list
ascFileList = arcpy.ListFiles("*.asc")
print ascFileList


for ascFile in ascFileList:
#geoprocessing steps
ascFileName = os.path.splitext (ascFile)[0]
print ascFileName
#works
rastFile = ascFileName + "_output.img"
print rastFile
#works
#run the tool
arcpy.ASCIIToRaster_conversion (env.workspace + "\\" + ascFile, env.workspace + "\\" +     rastFile, "INTEGER")
# Process: Projektion definieren
arcpy.DefineProjection_management (env.workspace + "\\" + rastFile,     "GEOGCS['GCS_WGS_1984',DATUM['D_WGS_1984',SPHEROID['WGS_1984',6378137.0,298.257223563]],PRI    MEM['Greenwich',0.0],UNIT['Degree',0.0174532925199433]]")
#list raster
rasters = arcpy.ListRasters("*", "IMG")
for ras in rasters:
    print "working..." + ras #works
    # new name
    name = "class_" + ras
    # Recalssify
    reclassField = "Value"
    remap = RemapValue ([["8",1],["2",0],["5",0]])
    outReclassify = Reclassify(ras, reclassField, remap, "NODATA")
    #save
    outReclassify.save (Dir + "\\" + name)

# Execute Plus
#outPlus = Plus(inRaster1, inRaster2)

I'm working with ArcMap 10.2.1.

2

To sum many rasters (> 2) together, I'd suggest using Cell Statistics. The example from ArcMap help:

# Execute CellStatistics
outCellStatistics = CellStatistics([inRaster01, inRaster02, inRaster03], "SUM", "NODATA")
# Save the output 
outCellStatistics.save("C:/sapyexamples/output/cellstats")

It is slightly trickier in your case since you have an arbitrary number of rasters in your list; I think, though, that you may be able to use a variable (e.g. populate a new list of reclassified rasters -- rcRasterList -- and put that into the CellStatistics function).

  • I think it is working with creating two layer using the tool 'plus': One for the rasterlist and the other for a single reclassified raster. But I can not trust the value at the moment. So I will try your way – thanks – Nora Aug 6 '14 at 13:25
  • Plus is designed to work with only two rasters, and if you feed it a list of rasters instead, I wouldn't expect it to work right. (Do let me know if my suggestion works or not, because I've never actually tried it with a list variable.) – Erica Aug 6 '14 at 13:32
  • I had a pretty hart time getting this cellstatistic tool working: I need to put in the hole new ListRaster for the toolinput at the second loop. ' outCellStat = CellStatistics (arcpy.ListRasters("class_2*"),"SUM", "NODATA")' – Nora Aug 7 '14 at 8:36
0

This is the result, it was kind of tricky for me!

import arcpy
import os
from arcpy import env
from arcpy.sa import *

arcpy.CheckOutExtension("Spatial")
env.overwriteOutput = True
env.workspace = r"D:\aufgabe_3\karadarya\2003\Step8"

#folder to list
ascFileList = arcpy.ListFiles("*.asc")
print ascFileList

for ascFile in ascFileList:
#geoprocessing steps
ascFileName = os.path.splitext (ascFile)[0]
print ascFileName
#works
rastFile = ascFileName + "_output.img"
print rastFile
#works
#run the tool
arcpy.ASCIIToRaster_conversion (env.workspace + "\\" + ascFile, env.workspace + "\\" +  rastFile, "INTEGER")
# Process: Projektion definieren
arcpy.DefineProjection_management (env.workspace + "\\" + rastFile,   "GEOGCS['GCS_WGS_1984',DATUM['D_WGS_1984',SPHEROID['WGS_1984',6378137.0,298.257223563]],PRI  MEM['Greenwich',0.0],UNIT['Degree',0.0174532925199433]]")
#list raster
# Execute Reclassify
reclassField = "Value"
remap = RemapValue ([["8",1],["2",0],["5",0]])
outReclassify = Reclassify(env.workspace + "\\" + rastFile, reclassField,remap,    "NODATA")
outReclassify.save (ascFileName+"_reclassified.img") #works

print "Ende Schleife"
recl_rasterlist = arcpy.ListRasters("*_reclassified*")

outCellStat = CellStatistics (recl_rasterlist,"SUM", "NODATA")
outCellStat.save(r"D:\aufgabe_3\result\cellStat2003.img")`
  • Could you please comment on this script (e.g. why this is useful, what is different, etc.)? – Aaron Aug 7 '14 at 17:06

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