NEARPOLY

 

calculates the distance from each polygon to the nearest neighboring polygon.  NEARPOLY is like the ARC NEAR command, except both the <in_cover> and {near_cover} contain polygons.

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NEARPOLY <in_cover> {near_cover} {search_radius} {out_cover} {cellsize}

 

ARGUMENTS

 

<in_cover> - the input polygon coverage.

 

The distance from each polygon is calculated to the nearest polygon in the {near_cover}.

 

{near_cover} - the second input polygon coverage.

 

The distance from each polygon in the <in_cover> is calculated to the nearest polygon in the {near_cover}.

 

If no {near_cover} is specified, then the <in_cover> is used as the {near_cover}, and the distance from each polygon in the <in_cover> is calculated to the nearest other polygon in the <in_cover>.

 

{search_radius} - the maximum distance to the nearest polygon.

 

If the {search_radius} is exceeded, then the nearest polygon is not reported.

 

{out_cover} - the name for the output coverage.

 

The {out_cover} is a copy of the <in_cover> with the addition of two items in the PAT: {near_cover}# and DISTANCE.

 

{near_cover}# contains the internal ID of the nearest polygon.  In the event that the {out_cover} and the {near_cover} both are the same as the <in_cover>, then the output item is named NEAR#, since {near_cover}# is already is use.

 

DISTANCE contains the distance to the nearest polygon.

 

If no {out_cover} is specified, then the items are added to the <in_cover> PAT.

 

{cellsize} - the size of the grid cells used to do the processing.

 

Enter the dimension of a single grid cell in map units.

 

If no {cellsize} is specified, it defaults to 1/1000th of the maximum dimension of the BND of the <in_cover>.

 

NEARPOLY converts the <in_cover> into a temporary grid in order to calculate the distance from each polygon to its nearest neighbor.  The smaller the {cellsize}, the better the results, and the longer the processing time.

 

 

NOTES

 

NEARPOLY runs from the ARC module of ARC/INFO, ver. 8.1.

 

In the <in_cover> and {near_cover}, polygons with User-IDs equal to 0 will not be included in the analysis.

 

 

EXAMPLES

 

Arc: &run nearpoly usage

Usage: NEARPOLY <in_cover> {near_cover} {search_radius} {out_cover} {cellsize}

 

Arc: &run nearpoly oldgrowth # # # 5