downstream

downstream

Cell gets value of the neighbouring downstream cell

Result = downstream(ldd, expression)

expression

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

ldd

spatial ldd

Result

spatial type of expression

Operation

For each cell, assigns to Result the expression value of the neighbouring downstream cell, where downstream cells are determined using the local drain directions on ldd. In case a cell doesn’t have a downstream cell (i.e. a pit) its own expression value is assigned to Result.

Notes

A cell with a missing value on ldd and/or expression is assigned a missing value on Result. Its upstream neighbours are assigned a missing value also.

Group

This operation belongs to the group of Neighbourhood operators; local drain directions

See Also

lddmask

Examples

1. • pcrcalc

   binding

   Result = Result.map;

   Ldd = Ldd.map;

   Expr = Expr.map;

   initial

   report Result = downstream( Ldd, Expr);

   
   

   • python

   Ldd = readmap(“Ldd.map”)

   Expr = readmap(“Expr.map”)

   Result = downstream( Ldd, Expr)

   Result.map	Ldd.map	Expr.map