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ArcGIS 10.2.2 arcpy Cell Statistics giving Incorrect Values

Question asked by palka005 on Mar 9, 2016
Latest reply on Mar 21, 2016 by palka005

Hey everyone, I've been having some issues using the cell statistics tool in a python script recently. The issue is occurring in a stand alone script. I am trying to calculate standard deviation across 30 tif's representing annual cumulative rainfall for the globe.

 

While most of the values in the resulting raster (also a tif) are correct, there are large pockets of data that have extremely high standard deviation values (around 2000 - 3000 when they should be around 150).

When I run the same analysis in ArcGIS using the cell statistics geoprocessing tool the output is correct and I do not see these irregular values.

 

Does anyone have any idea why this would be happening? I assumed at first it was something wrong with my script but how could only some of the values be incorrect? There are also no no data values in these issue areas that could be causing the miscalculation although there is a no data value set in all of the input rasters.

 

I am providing statistics on the two raster in case it is helpful to anyone.

script output:
min = 0
max = 6697.9404296875
mean = 75.83343676729601
std. dev. = 333.72000491046

 

arcmap output:
min = 0
max = 1507.4833984375
mean = 35.804817248754
std. dev. = 84.35107381816201

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