topic Re: Zonal statistics for raster using a matching mask file in ArcGIS Spatial Analyst Questions

Zonal statistics for raster using a matching mask file

MorganHarris — Tue, 27 Jan 2015 13:19:16 GMT

Hi again GeoNet community!

I have a question and the answer may involve script. Just a warning, I have very rarely dealt with scripting and so if the answer is a script code then I may need some extra guidance. Anyway, my problem is this:

I have about 1300 raster layers that I need to iterate through. For each raster layer, I need to run zonal statistics using a polygon layer. Each polygon layer corresponds to each raster in space and they also have the same file name (i.e. the raster name is 110_10R and the polygon file name is 110_10R as well, they are just saved in different folders. How can I make it so that 110_10R (raster) uses 110_10R (polygon) for its zonal statistics? Remember this needs to iterate 1300 times (actually 1300 x 12) so it needs to be 110_10R (raster) with 110_10R (polygon) then it moves on a runs 111_10R (raster) with 111_10R (polygon)...etc...

Remember, scripting novice, but I realize that it may be the only way to solve this issue

Thanks!

Re: Zonal statistics for raster using a matching mask file

JakeSkinner — Tue, 27 Jan 2015 15:26:19 GMT

Hi Morgan,

Where are the polygon feature classes/shapefiles located? Are they in the same directory as the rasters with the same name?

Re: Zonal statistics for raster using a matching mask file

MorganHarris — Tue, 27 Jan 2015 15:31:26 GMT

They are not in geodatabases or anything. They are just in different folders the pathnames may help you visualize how it is arranged in the directory?

Rasters:

C:\Users\AmyShipley\Desktop\Offline_2014_GIS\Exposure_Height

Polygons:

C:\Users\AmyShipley\Desktop\Offline_2014_GIS\shp_files\Distance_Buffers

Re: Zonal statistics for raster using a matching mask file

JakeSkinner — Sat, 11 Dec 2021 08:35:15 GMT

Something like below should get you started:

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

rasterWorkspace = r"C:\Users\AmyShipley\Desktop\Offline_2014_GIS\Exposure_Height"
polygonWorkspace = r"C:\Users\AmyShipley\Desktop\Offline_2014_GIS\shp_files\Distance_Buffers"

env.workspace = polygonWorkspace
shapefiles = arcpy.ListFeatureClasses("*", "Polygon")

env.workspace = rasterWorkspace
rasters = arcpy.ListRasters("*", "TIF")

for shapefile in shapefiles:
    shapefileName = shapefile.split(".")[0]
    for raster in rasters:
        rasterName = raster.split(".")[0]
        if rasterName == shapefileName:
            outZonalStats = ZonalStatistics(shapefileName, "value", rasterName, "SUM", "DATA")
            outZonalStats.save("zoneStats_" + shapefileName)

The above code will iterate through the raster workspace and find all TIFF files. If you are working with a different raster type, take a look at the ListRasters to change to the correct type, or simply remove "TIF" to use all rasters.

Re: Zonal statistics for raster using a matching mask file

MorganHarris — Tue, 27 Jan 2015 15:55:44 GMT

Great! Thanks, I will work with this and see what I can do with it!

Re: Zonal statistics for raster using a matching mask file

MorganHarris — Tue, 27 Jan 2015 16:02:03 GMT

Actually, one question before I get started working with this. After shapefile.split, what does (".") mean? Also, what should fill in the (" * ") space when defining the workspace? Does that stay as an asterisk so that it iterates through?

Re: Zonal statistics for raster using a matching mask file

JakeSkinner — Tue, 27 Jan 2015 16:08:14 GMT

Since you are working with Shapefiles, the name will be <name>.shp. The split method splits the shapefile name at the period and returns two values "<name>" and "shp" in a list. The [0] indicates to return the first value in the list. The same is true when dealing with a raster.

The "*" is a wildcard and will return all results when searching for shapefiles or rasters. If you just wanted to find a shapefile that began with "Pa", you could use:

shapefiles = arcpy.ListFeatureClasses("Pa*", "Polygon")

Re: Zonal statistics for raster using a matching mask file

MorganHarris — Tue, 27 Jan 2015 16:17:25 GMT

Ok, great, thanks for describing those for me

Re: Zonal statistics for raster using a matching mask file

MorganHarris — Fri, 30 Jan 2015 13:48:00 GMT

Ok, I've been trying to work with this code, but I must be doing something wrong. I have filled in the spaces with my own information and everything seems good to go, but when I hit enter nothing really happens. It doesn't give me errors or anything, but it also seems like it isn't doing anything. I have some specific questions below:

1) When I look at my raster files outside of arcmap they are each their own folder and have many files inside each folder that are .adf. Could this be a problem?

2) Is there a way to define where the data saves, and where is it saving right now so I can see if it did anything?

Thanks!

Re: Zonal statistics for raster using a matching mask file

JakeSkinner — Sat, 11 Dec 2021 08:35:18 GMT

1) It appears you are working with ESRI GRIDs. You will want to change:

rasters = arcpy.ListRasters("*", "TIF")

to:

rasters = arcpy.ListRasters("*", "GRID")

2) The rasters are saving to your env.workspace. You set this to your rasterWorkspace variable. So, the rasters should save here once once you make the change mentioned above.

Also, it's helpful to add print statements throughout your code. For example:

for shapefile in shapefiles:  
    shapefileName = shapefile.split(".")[0]  
    print shapefileName
    for raster in rasters:  
        rasterName = raster.split(".")[0]  
        print rasterName
        if rasterName == shapefileName:  
            outZonalStats = ZonalStatistics(shapefileName, "value", rasterName, "SUM", "DATA")  
            print "Saving raster"
            outZonalStats.save("zoneStats_" + shapefileName)

Re: Zonal statistics for raster using a matching mask file

MorganHarris — Fri, 30 Jan 2015 15:18:29 GMT

Sorry if I'm being a hassle! I converted some of my rasters to TIF just to mess with before I got your reply and have been just trying to get this to run, but I am getting the error shown below that says my input value raster isn't the right format or doesn't exist. The script is a little different since I have tweaked some things, but if you could take a look and see if you can tell what the problem is that would be great!

>>> import arcpy, os

... from arcpy import env

... from arcpy.sa import *

...

... rasterWorkspace = r"C:\Users\AmyShipley\Desktop\Offline_2014_GIS\Exp_Height_test_TIFF"

... polygonWorkspace = r"C:\Users\AmyShipley\Desktop\Offline_2014_GIS\shp_files\Distance_Buffers\Span_IDx10m_test_group"

...

... env.workspace = polygonWorkspace

... shapefiles = arcpy.ListFeatureClasses("*", "Polygon")

...

... env.workspace = rasterWorkspace

... rasters = arcpy.ListRasters("*", "TIF")

...

... for shapefile in shapefiles:

... shapefileName = shapefile.split(".")[0]

... for raster in rasters:

... rasterName = raster.split(".")[0]

... if rasterName == shapefileName:

... outZonalStats = ZonalStatistics(shapefileName, "FID", rasterName, "MINIMUM", "DATA")

... outZonalStats.save("zs_" + shapefileName)

...

Runtime error Traceback (most recent call last): File "<string>", line 19, in <module> File "c:\program files (x86)\arcgis\desktop10.2\arcpy\arcpy\sa\Functions.py", line 6145, in ZonalStatistics ignore_nodata) File "c:\program files (x86)\arcgis\desktop10.2\arcpy\arcpy\sa\Utils.py", line 47, in swapper result = wrapper(*args, **kwargs) File "c:\program files (x86)\arcgis\desktop10.2\arcpy\arcpy\sa\Functions.py", line 6138, in Wrapper ignore_nodata) File "c:\program files (x86)\arcgis\desktop10.2\arcpy\arcpy\geoprocessing\_base.py", line 498, in <lambda> return lambda *args: val(*gp_fixargs(args, True)) ExecuteError: Failed to execute. Parameters are not valid. ERROR 000860: Input value raster: is not the type of Composite Geodataset, or does not exist. Failed to execute (ZonalStatistics).

Re: Zonal statistics for raster using a matching mask file

JakeSkinner — Fri, 30 Jan 2015 15:31:09 GMT

Add some print statements as shown previously. It looks like it is failing when trying to run the ZonalStatistics for the intended raster. We will need to see what raster is being passed to this function. Adding "print rasterName" under "rasterName = raster.split(".")[0]" should help with this.

Re: Zonal statistics for raster using a matching mask file

MorganHarris — Fri, 30 Jan 2015 15:42:04 GMT

I added the print statements and it printed 10_100l for both shapefileName and rasterName, but then I still get the same error

>>> import arcpy, os

... from arcpy import env

... from arcpy.sa import *

...

... rasterWorkspace = r"C:\Users\AmyShipley\Desktop\Offline_2014_GIS\Exp_Height_test_TIFF"

... polygonWorkspace = r"C:\Users\AmyShipley\Desktop\Offline_2014_GIS\shp_files\Distance_Buffers\Span_IDx10m_test_group"

...

... env.workspace = polygonWorkspace

... shapefiles = arcpy.ListFeatureClasses("*", "Polygon")

...

... env.workspace = rasterWorkspace

... rasters = arcpy.ListRasters("*", "TIF")

...

... for shapefile in shapefiles:

... shapefileName = shapefile.split(".")[0]

... print shapefileName

... for raster in rasters:

... rasterName = raster.split(".")[0]

... print rasterName

... if rasterName == shapefileName:

... outZonalStats = ZonalStatistics(shapefileName, "FID", rasterName, "MINIMUM", "DATA")

... print "Saving raster"

... outZonalStats.save("zs_" + shapefileName)

...

10_100l

Runtime error Traceback (most recent call last): File "<string>", line 21, in <module> File "c:\program files (x86)\arcgis\desktop10.2\arcpy\arcpy\sa\Functions.py", line 6145, in ZonalStatistics ignore_nodata) File "c:\program files (x86)\arcgis\desktop10.2\arcpy\arcpy\sa\Utils.py", line 47, in swapper result = wrapper(*args, **kwargs) File "c:\program files (x86)\arcgis\desktop10.2\arcpy\arcpy\sa\Functions.py", line 6138, in Wrapper ignore_nodata) File "c:\program files (x86)\arcgis\desktop10.2\arcpy\arcpy\geoprocessing\_base.py", line 498, in <lambda> return lambda *args: val(*gp_fixargs(args, True)) ExecuteError: Failed to execute. Parameters are not valid. ERROR 000860: Input value raster: is not the type of Composite Geodataset, or does not exist. Failed to execute (ZonalStatistics).

Re: Zonal statistics for raster using a matching mask file

JakeSkinner — Fri, 30 Jan 2015 15:55:55 GMT

That was my mistake. We will need to add the full path to the shapefile. Replace the outZonalStats with the following:

outZonalStats = ZonalStatistics(polygonWorkspace + os.sep + shapefile, "FID", rasterName, "MINIMUM", "DATA")

The os.sep is simply python for a backslash.

Re: Zonal statistics for raster using a matching mask file

MorganHarris — Fri, 30 Jan 2015 16:59:45 GMT

Alright! Got it to work! I had to change the outZonalStats line to have the raster represented by the full path name too. I also ended up adding a line to get zonal stats as table and it worked out fine.

Thanks for your help!