Calc Pathway Map

Description

This functor calculates the shortest pathway between source features and an existing network of paths.

Inputs

Name	Type	Description
Network	Categorical Map Type	Map of the initial network of paths. Non-null value cells represent paths. If Network does not define a null value, this functor reports an error during execution.
Sources	Map Type	Map of the source features from which pathways are searched for. Features are represented by non-null values.
Costs Or Directions	Map Type	Map of the cost of building paths connecting the chosen destinations to the closest network, or map of the direction toward the least-cost cell from the current cell. Negative or zero costs indicate places where the network already exists.
Input Represents Directions	Boolean Value Type	If true, Costs Or Directions is assumed to represent cost directions; otherwise, it is assumed to represent costs. A cost-direction cell can only take the eight values corresponding to the directions of a Moore neighborhood: None=0, NW=1, N=2, NE=3, E=4, SE=5, S=6, SW=7, and W=8.

Optional Inputs

Name	Type	Description	Default Value
Use Lottery	Boolean Value Type	If true, and Input Represents Directions is false, ties for the lowest cost are broken randomly. This is an advanced port.	No
Merge Networks	Boolean Value Type	If true, the map of new paths is merged into the initial network map.	Yes

Outputs

Name	Type	Description
Network	Categorical Map Type	Map of the resulting network: the initial network map plus the new paths when Merge Networks is true, or just the new paths otherwise. Network has the same dimensions as the input Network map, and a single layer.

Group

Map Algebra

Notes

A source feature is ignored by the pathway search if the cost or direction cell at its starting position equals the null value; if the null value is found at any other cell along a path, this functor reports an error.

This functor reports an error if a local minimum is found on the cost map.

Sources uses Map Type, rather than Categorical Map Type, so that Calc Destination Map can be connected directly to it in a typical road-construction arrangement.

Internal Name

CalcPathwayMap

Usage examples

See practical examples of this functor in Lesson 17: Building a land-use and land-cover change simulation model