points2polygons
Batch point-in-polygon operations on GeoJSON files.
npm install points2polygons
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Version | 0.0.9 last updated 6 months ago |
License | MIT |
Repository | https://github.com/gabrielflorit/points2polygons.git (git) |
Bugs | https://github.com/gabrielflorit/points2polygons/issues |
Dependencies (7) | point-in-polygon, optimist, numeral, lodash, pace, csv2geojson, d3 |
points2polygons
Given a list of polygons and points, points2polygons
will determine if each point is inside a polygon, using point-in-polygon.
If found, the point will be added to the polygon.
For example:
Given a list of polygons, polygons.geojson
:
{
"type": "FeatureCollection",
"features": [
{
"type": "Feature",
"properties": { },
"geometry": {
"type": "Polygon",
"coordinates": [
[
[0,0],
...
and a list of points, points.csv
:
address, lat, lon
111 Point Lane, 1, 1
points2polygons
will assign points to matching polygons, and generate a new GeoJSON file:
{
"type": "FeatureCollection",
"features": [
{
"type": "Feature",
"properties": {
"points": [
{
"type": "Feature",
"properties": {
"address": "111 Point Lane"
}
"geometry": {
"type": "Point",
"coordinates": [1,1]
}
}
]
},
"geometry": {
"type": "Polygon",
"coordinates": [
[
[0,0],
...
Points with no polygons will be placed in their own GeoJSON file, orphans.geojson
.
Aggregation!
points2polygons
can perform sum and count aggregations. Let me explain. Say you have a town.geojson
:
{
"type": "Feature",
"properties": {
"name": "Polygonville"
},
"geometry": {
"type": "Polygon",
"coordinates": [
[
[0,0],
and houses.csv
:
address, color, value, latitude, longitude
111 Point Lane, red, 100, 1, 1
222 Point Lane, green, 200, 2, 2
333 Point Lane, red, 300, 3, 3
Running points2polygons --polygons town.geojson --points houses.csv
will correctly place the houses in our town, and generate something like this:
{
"type": "FeatureCollection",
"features": [
{
"type": "Feature",
"properties": {
"name": "Polygonville",
"points": [
// a house
{
"type": "Feature",
"properties": {
"address": "111 Point Lane",
"color": "red",
"value": "100"
}
"geometry": {
"type": "Point",
"coordinates": [1,1]
}
},
// another house
{
"type": "Feature",
"properties": {
"address": "222 Point Lane",
"color": "green",
"value": "200"
}
"geometry": {
"type": "Point",
"coordinates": [2,2]
}
},
...
]
},
"geometry": {
"type": "Polygon",
"coordinates": [
[
[0,0],
But what I really want is a count of red and green houses in my town. In other words, I want to
count
by color
. Use the --count
param. Running points2polygons --polygons town.geojson --points houses.csv --count color
generates something like this:
{
"type": "FeatureCollection",
"features": [
{
"type": "Feature",
"properties": {
"name": "Polygonville",
"green": 1, // there is one green house in the town
"red": 2 // there are two red houses in the town
},
"geometry": {
"type": "Polygon",
"coordinates": [
[
[0,0],
properties
doesn't contain points
anymore, only the aggregation result.
Pretty incredible! But what I really want is a total of house values, by color. In other words, I want to
sum
value
, and group by color
. Use the --groupBy
and --sum
params. Running points2polygons --polygons town.geojson --points houses.csv --groupBy color --sum value
generates something like this:
{
"type": "FeatureCollection",
"features": [
{
"type": "Feature",
"properties": {
"name": "Polygonville",
"green": 200, // this town's green houses are worth a total of 200
"red": 400 // this towns's red houses are worth a total of 400
},
"geometry": {
"type": "Polygon",
"coordinates": [
[
[0,0],
Pretty incredible!
Installation
npm install points2polygons
Using it as a console utility
➜ points2polygons
Batch point-in-polygon operations. Creates a GeoJSON file of polygons containing points.
Usage: points2polygons
Options:
-y, --polygons a GeoJSON file of polygons [required]
-t, --points a CSV file of points [required]
-i, --latitude latitude field [default: "latitude"]
-e, --longitude longitude field [default: "longitude"]
-d, --delimiter delimiter character [default: ","]
-o, --output a GeoJSON file of polygons containing points [default: "output.json"]
-c, --count aggregate points and count - group by this field [default: null]
-g, --groupBy aggregate points and sum - group by this field [default: null]
-s, --sum aggregate points and sum - sum this field [default: null]
Using it as a library
require('points2polygons')
.batch(polygons, points, showProgress, count, groupBy, sum)
polygons
: (required) a GeoJSON object of polygons.points
: (required) a GeoJSON object of points.showProgress
: (optional) a callback that gets fired per point processed, and receives the current point index.count
: (optional) if provided, will aggregate points and count this field. See example.groupBy
: (optional) if provided, will aggregate points and sum, grouping by this field. See example.sum
: (optional) if provided, will aggregate points and sum, summing by this field. See example.
Returns an object with two properties:
polygons
: same as input, but each polygon has apoints
property containing corresponding points.orphans
: a GeoJSON object containing points with no polygons.
See also
- point-in-polygon: determine if a point is inside a polygon.
- csv2geojson: magically convert csv files to geojson files.