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I have a raster file with classifcation codes, and want to reclassify valid codes to 1, and all others to 'NoData'.

RMAP2 = arcpy.sa.RemapValue([[3.2, 1],
                             [4.1, 1],
                             [4.2, 1]])

LCA = arcpy.sa.Reclassify(LCA, "LCCODE_USE", RMAP2, "NODATA")

The output however only contains the values 0 and 127, with the 0 value coinciding with just one of the missing values.

Any idea what the hell is going on?

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1  
I wouldn't trust a "3.2" in Python to translate, bit-by-bit, to the single precision float ArcGIS actually stores in that raster. That's asking too much. At a minimum you should be reclassifying narrow ranges of values, such as (3.15,3.25)-->1, (4.05,4.15)-->1, etc. But before even trying this, you ought to test your code with a simple, small, integer raster just to make sure you have correctly interpreted the syntax. Can you at least verify for us that such a test works and gets the right result? – whuber♦ Oct 22 '12 at 15:25
1  
I tried it on an integer raster, and yes it worked fine, so I floating point error makes sense. won't be able to test it out till Thursday though. – James Jenkinson Oct 23 '12 at 20:29

1 Answer

up vote 1 down vote

I think you are using the Reclass by Table (Spatial Analyst) geoprocessing tool instead of the plain Reclassify (Spatial Analyst) geoprocessing tool. The former takes a Table View containing the ranges of values to be reclassified; the latter utilizes the arcpy.sa.RemapValue Python objects to define the ranges of values to be reclassified.

So I think your code should be:

RMAP2 = arcpy.sa.RemapValue([[3.2, 1],
                             [4.1, 1],
                             [4.2, 1]])

LCA = arcpy.sa.Reclassify(LCA, "LCCODE_USE", RMAP2, "NODATA")

I can't test this for sure, since I don't have Spatial Analyst on the machine I'm using right now.

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Crud, sorry, I meant to edit that, I had actually been using Reclassify, but started rewriting it to Reclass by table before giving up and asking here. – James Jenkinson Oct 22 '12 at 14:42
So what's up above now is the actually code I was using. – James Jenkinson Oct 22 '12 at 14:45

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