I have a problem with Map Algebra in ArcMap 10 to convert some codes made by VB, so i need to convert it to python to work in arcmap 10 without problem. and can any one help me how do i deal with map algebra in arcmap10?

the code:

con([Direction to univer] > 0 & [Direction to univer] <= 180,[Direction to univer] + 180,[Direction to univer] - 180) 

Thank you.


You should be able to do the processing directly in python without much fuss:

import arcpy
from arcpy.sa import *

direction = Raster("direction-to-univer.tif")

output = con((direction > 0) & (direction <= 180), direction + 180, direction)
  • Thanks SCW, but i have a problem with line 4, arcmap crashed!!!!!
    – GIS Man
    Feb 17 '11 at 3:13
  • GIS Man: did it return an error? You'll also need to set the working environment with 'arcpy.env.workspace' which includes your raster, and change the 'direction-to-univer.tif' to the file you're trying to analyze.
    – scw
    Feb 17 '11 at 4:34
  • OK, thank you very much, i followed all steps but i have the same problem which arcmap crashed.this is all steps which i followed it:*Open ArcMap with raster layersopen python windowwrite code/ (import arcpy/arcpy.env.workspace = "E:/data/myproject/....."/from arcpy.sa import */direction = Raster("direction to univer")/output = con(direction > 0 && direction <= 180, direction + 180, direction), so the problem is here with finish output line specified 'last word "direction"'.
    – GIS Man
    Feb 18 '11 at 18:43
  • Unfortunately, the same error is exist!!!!!,i do not know, what can i do with this problem,i do all steps but the same error is exist.thanks
    – GIS Man
    Feb 18 '11 at 21:35
  • Could you try it again? I've updated the code to change how Con() is run as it doesn't seem to follow standard python syntax.
    – scw
    Feb 18 '11 at 23:19

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