Using d3.nest() with geojson files - d3.js

Question

How is d3.nest() used with geojson files?
My geojson data is formatted as follows:
"features": [
{ "type": "Feature", "properties": { "neighborhood": "Allerton", "boroughCode": "2", "borough": "Bronx", "#id": "http:\/\/nyc.pediacities.com\/Resource\/Neighborhood\/Allerton" }, "geometry": { "type": "Polygon", "coordinates": [ [ [ -73.848597000000183, 40.871670000000115 ], [ -73.845822536836778, 40.870239076236174 ], [ -73.854559184633743, 40.859953835764252 ], [ -73.854665433068263, 40.859585694988056 ], [ -73.856388703358959, 40.857593635304482 ], [ -73.868881809153407, 40.857223150158326 ], [ -73.868317552728243, 40.857862062258313 ], [ -73.869553714672321, 40.857784095600181 ], [ -73.871024857620654, 40.857309948816905 ], [ -73.870480549987164, 40.865413584098484 ], [ -73.87055489856489, 40.869702798589863 ], [ -73.86721594442561, 40.869689663636713 ], [ -73.85745, 40.869533000000182 ], [ -73.855550000000108, 40.871813000000145 ], [ -73.853597967576576, 40.873288368674203 ], [ -73.848597000000183, 40.871670000000115 ] ] ] } }
But my nest command:
var nested_data = d3.nest()
.key(function(d, i) { console.log(d); return d.features.properties.neighborhood; })
.entries(map);
returns an empty array.
I want to nest my data to more easily filter it. Is this advised?

Answer 1

Assuming your geojson looks like the below
var map = {
type: "FeatureCollection",
"features": [
{
"type": "Feature",
"properties": {
"neighborhood": "Allerton",
"boroughCode": "2",
"borough": "Bronx",
"#id": "http:\/\/nyc.pediacities.com\/Resource\/Neighborhood\/Allerton"
},
"geometry": { /* various coordinates, etc */ }
]
}
So, what you want to do is:
d3.nest()
.key(function(d, i) {
return d.properties.neighborhood;
})
.entries(map.features);
You want to pass map.features since that's your array.