Data Visualization & GIS at Eurostat. Exploring new ways of making maps.
Public
Edited
Oct 27, 2023
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area = r=>r.getJTSGeom().getArea() / 1e6
convexity = r=> {
return r.getJTSGeom().getArea() / r.getJTSGeom().convexHull().getArea()
}
circularity = r=> {
//compute radius of the circle with same area
const area = r.getJTSGeom().getArea()
const radius = Math.sqrt(area / Math.PI)
//build circle geometry, as buffer of the center
const cGeom = r.getJTSGeom().getCentroid().buffer(radius)
//compute intersection
let inter
try {
inter = cGeom.intersection(r.getJTSGeom())
} catch (error) {
//in case computation fails, run it on buffer(0)
inter = cGeom.buffer(0).intersection(r.getJTSGeom().buffer(0))
}
//return ratio
//console.log(r.properties.NUTS_NAME, inter.getArea()/area)
return inter.getArea() / area
}
circularity2 = r=> {
//TODO remove holes ? pre-simplify with closure ?
const radius = new jsts.algorithm.MinimumBoundingCircle(r.getJTSGeom()).getRadius();
const ca = Math.PI *radius *radius;
return r.getJTSGeom().getArea() / ca
}
circularity3 = r=> {
//it requires a simplified geometry - because the perimeter depends very much on the geometrical granularity.
const g = r.getJTSGeomSimplified()
//TODO remove holes ?
return 2*Math.sqrt(g.getArea()) / g.getLength()
}
elongation = r=> {
//get minimum bounding rectangle coordinates
const mbr = new jsts.algorithm.MinimumDiameter(r.getJTSGeom()).getMinimumRectangle().getCoordinates()
//compute length of two consecutive sides
const s1 = Math.hypot(mbr[0].x-mbr[1].x, mbr[0].y-mbr[1].y)
const s2 = Math.hypot(mbr[1].x-mbr[2].x, mbr[1].y-mbr[2].y)
const e = s1>s2? s2/s1 : s1/s2
return 1-e
}
orientationElongationThreshold = 0.333
orientation = r => {
//get minimum bounding rectangle coordinates
const mbr = new jsts.algorithm.MinimumDiameter(r.getJTSGeom()).getMinimumRectangle().getCoordinates()
//compute length of two consecutive sides
const s1 = Math.hypot(mbr[0].x-mbr[1].x, mbr[0].y-mbr[1].y)
const s2 = Math.hypot(mbr[1].x-mbr[2].x, mbr[1].y-mbr[2].y)
//compute elongation
let e = s1>s2? s2/s1 : s1/s2
e = 1-e
//if elongation not sufficient, then measure not defined
if(e < orientationElongationThreshold) return undefined;
//compute angle of the length, in radian
let a = s1>s2?
Math.atan2(mbr[0].y-mbr[1].y, mbr[0].x-mbr[1].x) :
Math.atan2(mbr[1].y-mbr[2].y, mbr[1].x-mbr[2].x)
//in degree, within [0,180]
a = a * 180 / Math.PI
if(a<0) a+=180
return a
}
rectangleness= r => {
//compute minimum bounding rectangle
const mbr = new jsts.algorithm.MinimumDiameter(r.getJTSGeom()).getMinimumRectangle()
//compute areas
const area = r.getJTSGeom().getArea()
const mbrArea = mbr.getArea()
//compute center
const c = r.getJTSGeom().getCentroid().getCoordinate()
//compute scale ratio
const scaleRatio = Math.sqrt(area/mbrArea)
//build scale transform
const at = new jsts.geom.util.AffineTransformation()
at.translate(-c.x, -c.y)
at.scale(scaleRatio,scaleRatio)
at.translate(c.x, c.y)
//scale MBR
const scaledMBR = at.transform(mbr)
//check scaled mbr and region have same are
//console.log(scaledMBR.getArea()- area)
//compute intersection
let inter
try {
inter = scaledMBR.intersection(r.getJTSGeom())
} catch (error) {
//in case computation fails, run it on buffer(0)
inter = scaledMBR.buffer(0).intersection(r.getJTSGeom().buffer(0))
}
//return ratio
//console.log(r.properties.NUTS_NAME, inter.getArea() / area)
return inter.getArea()/area
}
rectangleness2 = r => {
//get minimum bounding rectangle
const mbr = new jsts.algorithm.MinimumDiameter(r.getJTSGeom()).getMinimumRectangle()
return r.getJTSGeom().getArea() / mbr.getArea()
}
squareness = r => {
const rect = rectangleness(r)
const elong = elongation(r)
return rect * (1-elong)
}
regionsJSTS = regionsFiltered.map(r=>{
//create jts version of the geometry
r.getJTSGeom = () => {
if(!r.jtsGeom__) r.jtsGeom__ = GJreader.read(r.geometry)
return r.jtsGeom__
}
//create generalised version of the geometry
r.getJTSGeomSimplified = () => {
if(!r.jtsGeomSimplified__) {
r.jtsGeomSimplified__ = r.getJTSGeom()
//simplification parameter: the geometry diagonal divided by nb of pixels
const d = r.getJTSGeom().getEnvelopeInternal().getDiameter();
const res = 0.7 * d/regionWidth
//simple generalisation process: ramer-douglass-peucker filter, with erosion/closure
r.jtsGeomSimplified__ = jsts.simplify.DouglasPeuckerSimplifier.simplify(r.jtsGeomSimplified__, 0.5*res)
r.jtsGeomSimplified__ = r.jtsGeomSimplified__.buffer(2*res)
r.jtsGeomSimplified__ = jsts.simplify.DouglasPeuckerSimplifier.simplify(r.jtsGeomSimplified__, 1*res)
r.jtsGeomSimplified__ = r.jtsGeomSimplified__.buffer(-2*res)
r.jtsGeomSimplified__ = jsts.simplify.DouglasPeuckerSimplifier.simplify(r.jtsGeomSimplified__, 1*res)
}
return r.jtsGeomSimplified__
}
return r;
})
regionsMeasured = regionsJSTS.map(r=>{
try {
r.measure = measureFun(r)
} catch (error) {
console.log("Failed computing measure for ",r.properties.name,r.properties.NAME_LATN)
r.measure = undefined
}
return r
})
regionsFilteredSorted =
regionsMeasured
.filter( r=> r.measure != undefined )
.sort(function (r1, r2) {
return r1.measure - r2.measure;
})
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