Extract by Attributes error with extract.save

Question

On the following code block (specifically, the last line), IDLE throws this error:

ERROR 010093: Output raster format UNKNOWN is unsupported.
for raster in arcpy.ListRasters(): 
    outpoint = workspace + raster + "af"
    extract = arcpy.sa.ExtractByAttributes (raster, " VALUE = 6 OR VALUE = 8")
    extract.save (outpoint)

I feel like it shouldn't be necessary to specify a format since the output is saving into a geodatabase. Also, is there better documentation on extract.save somewhere? I've found very little on it and am just imitating the syntax example used on the Extract by Attributes tool page.

ThomasLaxson · Answer

This error (010093) often occurs when trying to create an improperly named raster file. For GRIDs, the naming restrictions include:...a grid should not be named with spaces or any other special characters in its name. A multiple-band grid cannot have more than 9 characters in its file name, and a single-band raster dataset cannot have more than 13 characters.

Todd, this probably applies in your case, if you're using HUC 12s; the appending of your four characters ('fdr_') puts you over the 13 character limit.

See ESRI's help page on GRIDs for more info.

curtvprice · Answer

A few things to keep in mind:* Although Spatial Analyst tools now do direct read/write of many formats, grid (folder workspace) is usually still the best choice.
* The workspace and scratchWorkspace should be set to the same folder for best performance.
* Grid format is limited to 13-characters, alphanumeric + "_", starting with a letter.
* Workspace, feature class, table, and field names should never begin with a number.

MarcinGasior · Answer

I believe you shold use "\" instead of "/" in this line.

BTW, os module prowides very convenient method for constructing pathes - join. In your case it will be:outRaster = os.path.join(FDRpath, "fdr_" + "HUC")
FdrOut.save(outRaster)

The same way you can construct FDRpath and FACpath variables.