POINTAGGREGATE

 

Aggregate clusters of points into single points.

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POINTAGGREGATE <in_cover> <out_cover> <aggregation_distance> {aggregation_item} {selection_file} {min_perimeter} {<summary_item> <statistic>.<summary_item> <statistic>}

 

ARGUMENTS

 

<in_cover> - the input point coverage.

 

<out_cover> - the name for the output point coverage.

 

<aggregation_distance> - the maximum distance (in map units) between a point in an cluster and the nearest other point in the same cluster.

 

{aggregation_item} - the item in the <in_cover> PAT used to group points.  Only points that have the same {aggregation_item} value can be part of the same cluster.

 

If no item is specified, then all points are considered part of the same group.

 

{selection_file} - the ARCPLOT selection file that identifies which points are to be considered for aggregation.

 

All points not listed in the selection file are retained in the <out_cover> and are not subject to aggregation.

 

If no selection file is specified, then all points are considered for aggregation.

 

{min_perimeter} - the minimum perimeter (in map units) around each cluster of points.

 

Clusters with perimeters less than the {min_perimeter} will not be aggregated into one point, but instead all points within such clusters will be retained in the <out_cover>.

 

Clusters with perimeters that are greater than or equal to the {min_perimeter} will be aggregated into one point at the center of the polygon that surrounds the cluster.

 

The polygon that surrounds each cluster is formed by buffering all of the points in the cluster by « the <aggregation_distance>.

 

<summary_item> - an item in the <in_cover> PAT that whose values will be determined in the <out_cover> PAT using the <statistic> to summarize the values of all points that fall into the same cluster.

 

All items that are not specified are still retained in the <out_cover> PAT, and the MODE <statistic> is used to summarize the values.

 

<statistic> - the statistic used to summarize the <summary_item> values.

 

Choices are: MODE, SUM, MEAN, MIN, and MAX.

 

Only MODE can be used with non-numeric items.

 

 

NOTES

 

POINTAGGREGATE runs from the Arc module of ArcInfo.

 

 

EXAMPLES

 

Arc: &run pointaggregate

Usage: POINTAGGREGATE <in_cover> <out_cover> <aggregation_distance> {aggregation_item} {selection_file} {min_perimeter} {<summary_item> <statistic>.<summary_item> <statistic>}

 

1)  To aggregate points that share the same CFF code, are no more than 40 meters apart, and form clusters with perimeters of at least 320 meters:

 

Arc: &run pointaggregate kell_pt kell_pt2 40 cff1 320