if then

if then

Return missing values if condition is not met.

# Python
Result = ifthen(condition, expression)

# PCRcalc
Result = if(condition then expression)
Result = if(condition, expression)

expression

spatial, non spatial boolean, nominal, ordinal, scalar, directional, ldd

condition

spatial, non spatial boolean

Result

Python:

spatial; type of expression

PCRcalc:

spatial; if condition and expression are non spatial non spatial type of expression

Operation

The cell values on condition are interpreted as Boolean values where 1 is TRUE and 0 is FALSE. For each cell, the cell value on condition determines whether the value of the corresponding cell on expression or a missing value is assigned to the corresponding cell on Result: if condition has a cell value 1 (TRUE) the value on expression is assigned to Result, if condition has a cell value 0 (FALSE) a missing value is assigned to Result.

Notes

A cell with missing value on condition and/or expression results in a missing value on Result at the corresponding cell. A comma between condition and expression in the command line is an alternative notation for then.

If you want to cut an local drain direction map (data type ldd), use the operator lddmask instead of if then. The operator if then allows for cutting an expression of data type ldd, but we advice to use it in very special cases only; it will result in an unsound ldd.

Group

This operation belongs to the group of Conditional operators

See Also

if then (else) pitfalls, cover, defined, lddmask

Examples

1. • pcrcalc

   binding

   Result = Result.map;

   Cond = Cond.map;

   Expr1 = Expr1.map;

   initial

   report Result = if(Cond then Expr1);

   
   

   • python

   Cond = readmap(“Cond.map”)

   Expr1 = readmap(“Expr1.map”)

   Result = ifthen(Cond, Expr1)

   Result.map	Cond.map	Expr1.map