clump

clump

Contiguous groups of cells with the same value (‘clumps’)

Result = clump(expression)

expression

spatial boolean, nominal, ordinal

Result

spatial nominal

Options

--diagonal or --nondiagonal

--diagonal

cells of the same value are grouped if they are within the immediate 8-cell neighbourhoodnof each other. This includes if they are to the right or left, above or below,nor are diagonal to each other (eight nearest neighbours, default).

--nondiagonal

cells of the same value are grouped only if the cells are directly to the rightnor left, or above or below each other (four nearest neighbours).

Operation

Cells that have the same value on expression and are neighbours are grouped. Every group of cells satisfying these conditions is assigned a unique value on Result. Cells without neighbours with the same value on expression are also assigned a unique value on Result. The kind of connectivity needed for cells to be neighbours is specified by the option.

Notes

Cells with a missing value on expression are assigned a missing value on Result.

Group

This operation belongs to the group of Area operators

Examples

1. • pcrcalc

   binding

   Result1 = Result1.map;

   Expr = Expr.map;

   initial

   report Result1 = clump( Expr);

   
   

   • python

   Expr = readmap(“Expr.map”)

   Result1 = clump( Expr)

   Result1.map	Expr.map

   
   
2. • pcrcalc

   #! –nondiagonal

   binding

   Result2 = Result2.map;

   Expr = Expr.map;

   initial

   report Result2 = clump( Expr);

   
   

   • python

   setglobaloption(“nondiagonal”)

   Expr = readmap(“Expr.map”)

   Result2 = clump( Expr)

   Result2.map	Expr.map