topic Re: IDW in arcpy not working in ArcGIS Spatial Analyst Questions

IDW in arcpy not working

Fsbei — Thu, 17 Mar 2022 14:39:24 GMT

Hello all,

First post after many years of lurking. I am currently building a workflow in python. I am trying to use IDW to create a wind direction map. The input is a fc containing the location of weatherstations and the recorded wind directions. When I run the IDW tool from arcgis itself it works fine. However, when I try to recreate the map using arcpy I keep getting a raster with a single value. All parameters are the same in both the arcgis desktop and the arcpy script.

Is there a known issue with IDW when using arcpy?

See extract from script below:

input_tbl = r'...windspeed.csv'
workspace = r'...\scratch.gdb'
#environment settings
arcpy.env.workspace = workspace
arcpy.env.overwriteOutput = True
spatial_ref = arcpy.SpatialReference(4326)
out_weatherstations = arcpy.management.XYTableToPoint(input_tbl,'weather_stations','long','lat','',spatial_ref)
print('point created')
out_IDWdirection = arcpy.sa.Idw(out_weatherstations,
"direction_degrees",
2000,
2,
'VARIABLE 12',
None);
out_IDWdirection.save(r'/...IDW_direction')

Re: IDW in arcpy not working

SteveLynch — Thu, 17 Mar 2022 14:47:44 GMT

- how many columns and rows does the output raster have?

- do the input points display within the extent of the raster?

- include a print of the number of records in out_weatherstations, use GetCount, in your script to see how many points are going into IDW

Re: IDW in arcpy not working

Fsbei — Thu, 17 Mar 2022 15:11:42 GMT

Thanks @SteveLynch . Your comment on the extent made me look more closely to the environment settings within the script. Simply stating the extent didn't work but stating that the env outputs spatial reference must be set to UTM did the trick! Within the arcgis project I had already set my environmental settings but ofcourse this was not set within the script. I think the cause of the empty output is that the IDW was calculated within the WGS84 ref. This of course can cause some conflicts with the given values I provided.

Re: IDW in arcpy not working

RachelGomez — Wed, 30 Nov 2022 07:32:46 GMT

Repair ArcMap using one of the following steps: Rerun the installation tool, and click the Repair radio button. Navigate to the Control Panel > Programs > Programs and Features > Uninstall a program, and double-click ArcGIS for Desktop. Click the Repair radio button.

Regards,

Rachel Gomez