Aggregate properties of GeoJSON polygons, grouped by another set of polygons
npm install geojson-polygon-aggregate
var aggregate = require('geojson-polygon-aggregate')
var groups = { /* geojson FeatureCollection of polygons */ }
var data = { /* geojson FeatureCollection of polygons with some data */ }
// assumes that the features in data have a numeric property called 'something'
var result = aggregate.groups(groups, data, {
'something': aggregate.reducers.sum('something'),
'something-area-weighted': aggregate.reducers.areaWeightedSum('something'),
'area': aggregate.reducers.totalArea(),
'count': aggregate.reducers.count(),
'arbitraryProperty': function (memo, feature) {
// the aggregations above are provided for convenience, but you can
// do whatever you want here. `memo` is the previous return value
// of this function, or groups.properties['arbitraryProperty'] on the
// first iteration.
if (memo) {
return memo + ', ' + feature.properties['something']
} else {
return 'Values: ' + feature.properties['something']
}
}
})
Aggregate properties of GeoJSON polygon features.
Parameters
data
(FeatureCollection.<Polygon>|Array) The polygons to aggregate.features
aggregations
Object The aggregations as key-value pairs, where the key is the name of the resulting property, and the value is the reducer function with signature (accumulator, clippedFeature, groupingFeature, additionalArgs[0], additionalArgs[1], ...) => accumulatorthisArg
Object= Optional 'this' context with which to call reducer functionsadditionalArgs
Array= Optional array of additional args with which to call reducer functions
Returns Object A properties object with the aggregated property values
Aggregate properties of GeoJSON polygon features, grouped by another set of polygons.
Parameters
groups
(FeatureCollection.<Polygon>|Array) The polygons by which to group the aggregations.data
(FeatureCollection.<Polygon>|Array) The polygons to aggregate.aggregations
Object The aggregations as key-value pairs, where the key is the name of the resulting property, and the value is the reducer function with signature (accumulator, clippedFeature, groupingFeature, additionalArgs[0], additionalArgs[1], ...) => accumulatorthisArg
Object= Optional 'this' context with which to call reducer functionsadditionalArgs
Array= Optional array of additional args with which to call reducer functions
Returns FeatureCollection.<Polygon> A set of polygons whose geometries are identical to groups
, but
with properties resulting from the aggregations. Existing properties on features in groups
are
copied (shallowly), but aggregation results will override if they have the same name.
Aggregate properties of streaming GeoJSON polygon features.
Parameters
aggregations
Object The aggregations as key-value pairs, where the key is the name of the resulting property, and the value is the reducer function with signature (accumulator, clippedFeature, groupingFeature, additionalArgs[0], additionalArgs[1], ...) => accumulatorthisArg
Object= Optional 'this' context with which to call reducer functionsadditionalArgs
Array= Optional array of additional args with which to call reducer functions
Returns Object A transform stream reading GeoJSON feature objects and, writing, at the end, a properties object with the aggregated property values
This module relies heavily on the fantastic Turf.js project. If it doesn't do what you need, something over there very likely does!