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Can you please show me how to construct the decision tree for the attached land cover classification.
I assume it is nested Con statement, but I am confused on how to write the statement.

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is your data vector or raster (probably raster if you mention Con, but just to make sure) ? – radouxju Feb 15 '14 at 18:48
My data is raster ( DEM Image, Precipitation, etc.) – Kaleab Feb 15 '14 at 19:05

The con statement has the following syntax :

Con ( condition, value_if_true , value_if_false)

A "one liner" would be very long, but possible. However it is sometimes better to do several steps.

Here is a start, to give you the idea: the main difficulty is then to place the parentheses at the right place.

Con ( "AET" < 0.4 ,  Con ("AET" < 0.15 , 1 , 2 ) , Con ( "MTCM" < 17 , 3 , Con ( "to_be_continued") )  )

1 is for desert, 2 is for semi-Arid, 3 is for mountain... (you store integers in rasters, you can create a look up table after).

"AET" is an example of name, you can use the layer name or the full path)

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,thanks for the help. i had the raster but it is coarse resolution. How can we use vector data (shapefile) for the same decision-tree? – Kaleab Feb 16 '14 at 4:24
for vector, you should post another question and describe your input data in order to get an appropriate answer, and to fit with the QA rules of this site. – radouxju Feb 17 '14 at 20:39

If your datasets are vector consider using the Union tool. The output will have all combinations of polygons with the original attribution. I am assuming you have the advanced level license.

Then you could create some sort of nested if-then field calculation to assign the land type.

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