Full stack web developer & lecturer. Data visualization. Vue, React, D3 & more
Published
Edited
Feb 10, 2021
3 stars
malta_id = countryCode("MLT")
malta110 = countries110.objects.countries.geometries.find(e => e.id === malta_id)
malta50 = countries50.objects.countries.geometries.find(e => e.id === malta_id)
arcs = malta50.arcs.flat(2)
arcs_geometry = arcs.map(pos => countries50.arcs[pos])
function transformPoint([x,y]){
const oldTransform = countries50.transform
const newTransform = countries110.transform
const newX = (x * oldTransform.scale[0] + oldTransform.translate[0] - newTransform.translate[0]) / (newTransform.scale[0])
const newY = (y * oldTransform.scale[1] + oldTransform.translate[1] - newTransform.translate[1]) / (newTransform.scale[1])
return [newX, newY]
}
function transformScale([x,y]){
const oldTransform = countries50.transform
const newTransform = countries110.transform
const newX = (x * oldTransform.scale[0]) / (newTransform.scale[0])
const newY = (y * oldTransform.scale[1]) / (newTransform.scale[1])
return [newX, newY]
}
transformed_arcs = arcs_geometry.map(([first, ...rest]) => [transformPoint(first), ...rest.map(transformScale)])
current_length = countries110.arcs.length
merged_topojson.arcs.push(...transformed_arcs)
merged_topojson.arcs.slice(-transformed_arcs.length)
mapped_arcs = arcs.reduce((o, key, i) => ({ ...o, [key]: current_length + i}), {})
malta50
malta_copy = {
const malta_copy = JSON.parse(JSON.stringify(malta50));
malta_copy.arcs = malta_copy.arcs.map(e => e.map(e => e.map(e => mapped_arcs[e])))
return malta_copy
}
merged_topojson.objects.countries.geometries.push(malta_copy)
merged_topojson
final_topojson = {
const final_topojson = merged_topojson
final_topojson.arcs.push(...transformed_arcs)
final_topojson.objects.countries.geometries.push(malta_copy)
return final_topojson
}
chart = {
const svg = d3.create("svg").attr("viewBox", [0, 0, width, height]);
const countriesPath = svg.append("path")
.datum(countries)
.attr("fill", "none")
.attr("stroke", "black")
.attr("stroke-width", 0.5)
.attr("stroke-linejoin", "round")
.attr("d", path);
const zoomed = ({ transform }) => {
countriesPath.attr('transform', transform)
countriesPath.attr('stroke-width', 0.5 / transform.k)
}
const zoom = d3.zoom().scaleExtent([1, 32]).on('zoom', zoomed)
svg.call(zoom)
return svg.node();
}
height = 500
projection = d3.geoNaturalEarth1()
path = d3.geoPath(projection)
countries = topojson.feature(final_topojson, final_topojson.objects.countries)
d3 = require("d3")
topojson = require("topojson-client")
codes = FileAttachment("country-codes.json").json()
countryCode("FRA")
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