rivers = FileAttachment("ne_50m_rivers_lake_centerlines.json").json()
Object.keys(rivers.features[0].properties)
scaleRankExtents = d3.extent(rivers.features, (d) => d.properties.scalerank)
srScale = d3.scaleLinear().domain(scaleRankExtents).range([1, 0])
d3.range(1, 13).map((d) => d3.interpolateBlues(srScale(d)))
d3 = require("d3", "d3-geo", "d3-geo-projection", "d3-geo-polygon")
projection = d3
.geoWinkel3()
.rotate([lonRotation, latRotation])
.scale(scale)
.translate([width / 2, height / 2])
path = d3.geoPath().projection(projection)
// Many map projections are 2:1 aspect ratio, conforming to the longitude:latitude ratio.
// This is just a best guess, as an appropriate value would depend on the specific projection used.
height = width / 2
map = {
//svg container
const svg = d3.create("svg").attr("width", width).attr("height", height);
//background rect
svg
.append("rect")
.attr("width", width)
.attr("height", height)
.attr("fill", bgColor);
//There is a special geojson data type called "Sphere" which is often used to fill in the whole planet regardless of projected shape.
//So it's good as a background!
svg
.append("path")
.datum({ type: "Sphere" })
.attr("d", path)
.attr("fill", earthColor);
//add SVG group to keep things neat
svg
.append("g")
//standard data join
.selectAll(".rivers")
.data(rivers.features)
.enter()
.append("path")
.attr("d", path)
.attr("stroke", (d) => d3.interpolateBlues(srScale(d.properties.scalerank)))
.attr(
"stroke-width",
(d) =>
maxRiverThickness * srScale(d.properties.scalerank) + minRiverThickness
)
.attr("fill", "none")
.attr("class", "rivers");
return svg.node();
}
One platform to build and deploy the best data apps
Experiment and prototype by building visualizations in live JavaScript notebooks. Collaborate with your team and decide which concepts to build out.
Use Observable Framework to build data apps locally. Use data loaders to build in any language or library, including Python, SQL, and R.
Seamlessly deploy to Observable. Test before you ship, use automatic deploy-on-commit, and ensure your projects are always up-to-date.