How to calculate

with undefineds in maps and tables

You might wish to:

test for undefined values, class names or IDs in maps or columns and assign those another value, class name or ID, or
assign undefined values, class names or IDs to certain existing values, classes or IDs.

Testing for undefineds:

To test for undefined values, use the ISUNDEF function. The ISUNDEF function tests whether a is undefined. Argument a can be the outcome of an expression or simply a map or column name. Below, the ISUNDEF function is combined with a conditional IFF.

Result1 = IFF (ISUNDEF(Landuse), "Mountains", Landuse)

Result2 = IFF (ISUNDEF(Population), 1000, Population)

First formula (on a domain Class map or column):

If a pixel in map Landuse is undefined, then class name "Mountains" is assigned to this pixel in map Result1; else the original class name is assigned. Same for fields in column Landuse.

Second formula (on a domain Value map or column):

If a pixel of map Population is undefined, then value 1000 is assigned to this pixel in map Result2; else the original population value is assigned. Same for fields in column Landuse.

Tip: You can also use the IFUNDEF function.

Assigning undefined values:

To assign undefined values, use a question mark when the output domain is a domain Value, and use a question mark in between double quotes when the output domain is a domain Class or ID.

Result3 = IFF(Landuse = "Mountains", "?", Landuse)

Result4 = IFF(Population = 1000, ?, Population)

Third formula (output domain Class or ID):

If a pixel in map Landuse has class name "Mountains", then undefined is assigned to this pixel in map Result3; else the original class name is assigned. Same for fields in column Landuse.

Fourth formula (output domain Value):

If a pixel in map Population has value 1000, then undefined is assigned to this pixel in map Result4; else the original Population value is assigned. Same for fields in column Landuse.