New module proposal @turf/filter

New module proposal @turf/filter

This module should return true/false if the Feature should be filtered based on the GeoJSON properties.

This type of behavior is already being used in @turf/clusters & @turf/dissolve, this module would replace the filter functionality within these two modules and act as a stand alone module with it’s own independent testing.

Could also call this module @turf/boolean-filter since the output will strictly be a boolean.

How to use module

const {point} = require('@turf/helpers')
const filter = require('@turf/filter')

const pt = point([10, 20], {foo: 'bar'})
filter(pt, {foo: 'bar'})
//=true
filter(pt, {hello: 'world'})
//=false

Source code

• @turf/clusters
• @turf/dissolve

Tests

• @turf/clusters

Ref: https://github.com/Turfjs/turf/pull/907#issuecomment-324851611

[andrewharvey]

I’d rather not call this filter as I naturally would expect it to behave like Array.filter.

I came here to suggest we implement the equivalent of the JS filter function.

var onlyPoints = turf.filter(geojson, (feature) => {
    return turf.getType(feature) === 'Point';
})

along with map

var ids = turf.map(geojson, (feature, index) => {
    feature.id = index;
    return feature;
})

The advantage of doing this with turf rather than straight JS is the corner cases of where GeoJSON is just one feature rather than a feature collection is abstracted.

[rowanwins]

interesting idea @DenisCarriere , some of those more extended uses could certainly be nifty