Calculate Map

Description

This container calculates a map using algebraic/logical expression involving maps, tables and values.

Inputs

Name	Type	Description
Expression	Image Expression	Algebraic or logical expression used to calculate the output map.

Optional Inputs

Name	Type	Description	Default Value
Cell Type	Cell Type	Data cell type	Signed 32 Bit Integer
Null Value	Null Value	Null value	Default1) Based on the value of the Cell Type input.
Result Is Sparse	Bool	If true, the resulting map is created as a sparse image. Sparse images have the advantage of storing only the cells containing non-null values, but they have diminished access time.	False
Result Format	Map	Map representing the output format. Any category information presents in the given map is not used as part of the map format.	None

Outputs

Name	Type	Description
Result	Map	Output map.

Group

Map Algebra

Notes

The expression result is calculated as a real value and converted to the data cell type of the output map.

If the calculation of the expression diverges, the corresponding cell is filled with the null value. In practice, it means that every time a null value is found in a expression calculation, the calculation results in null value, unless the occurrence of the null value is isolated from the rest of the expression by a special operator like isNull() or ?.

The examples below illustrates:

Example	Analysis
i1 / 0	The expression always results in null value.
i1 + i2 / i3 ^ 3	If the current cell of any of the images involved in the calculation is null value, the expression results in null value .
if isNull(i1) then 1 else 2	The expression never results in null value.
if isNull(i1) then i2 else i3	The expression might result in null value depending on the the value of i2 and i3.
(100 / i2) ? 0	The expression never results in null value.
(100 / i2) ? i1	The expression might result in null value depending on the the value of i1.

If the data cell type is not large enough, the corresponding cell is also filled with the null value.

The list of mathematical and logical operators that can be employed in the logic/algebraic expression can be found in the image expression reference.

The maps used by the “Calculate Map” must be provided by a corresponding Number Map, the tables must be provided by a corresponding Number Table and the values must be provided by a corresponding Number Value.

Internal Name

CalculateMap