Building and Using Tools to See.
UVA Architecture + Data Science. IT Director. Instructor.
Public
Edited
Apr 22, 2024
locations = [
{name: "Charlottesville", lon: -78.4767, lat: 38.0293},
{name: "Wise", lon: -82.5757, lat: 36.9759},
{name: "Chincoteague", lon: -75.3788, lat: 37.9332},
{name: "Washington, D.C.", lon: -77.0369, lat: 38.9072},
{name: "Baltimore", lon: -76.6122, lat: 39.2904}
]
d3.geoContains(vaGeoJSON,[locations[0].lon,locations[0].lat]) // just to show the true/false return.
virginia = usstates.features.filter(d => d.properties.NAME == "Virginia") // extracted state feature from usstates
vaGeoJSON = subsetGeoJSON(virginia) // build a full geoJSON object from feature(s), required by d3.geoContains()
subsetGeoJSON = (features) => {
// build a complete geoJSON object from only passed in features.
let geoJSON = Object();
geoJSON.type = "FeatureCollection";
geoJSON.idField = "properties.NAME";
geoJSON.features = Array();
features.forEach(d => {
geoJSON.features.push(d);
});
return geoJSON;
}
map = d3.select(mapContainer)
{
let mapLayers = [];
mapLayers["virginia"] = drawMapLayer(map,"virginia",virginia,"properties.NAME");
let dots = d3.select(mapContainer).selectAll("circle")
.data(locations)
.join("circle")
.attr("r",5)
.attr("cx", d => projection([d.lon,d.lat])[0])
.attr("cy", d => projection([d.lon,d.lat])[1]);
let labels = d3.select(mapContainer).selectAll("text")
.data(locations)
.join("text")
.attr("x", d => projection([d.lon,d.lat])[0] + 10)
.attr("y", d => projection([d.lon,d.lat])[1])
.text(d => d3.geoContains(vaGeoJSON,[d.lon,d.lat])); // true or false text label
}
projection = d3.geoMercator().center([-79,38]).scale(5000)
import {getMapData, drawMapLayer} with {projection} from "@emfielduva/dvlib_maps"
usstates = getMapData("us_states20m")
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