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July 26, 2021 09:28
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format Arctic sea ice Polygon data
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| const fs = require('fs'); | |
| const geojson = JSON.parse(fs.readFileSync('./input.geojson', 'utf8')); | |
| const splitIndexes = []; | |
| geojson.features.forEach(a => { | |
| const _data = []; | |
| a.geometry.coordinates.forEach(b => { | |
| const __data = []; | |
| b.forEach((c, i) => { | |
| if (i !== 0 && Math.abs(c[0] - b[i - 1][0]) > 180) __data.push(i); | |
| }) | |
| _data.push(__data); | |
| }) | |
| splitIndexes.push(_data); | |
| }) | |
| geojson.features.forEach((a, l) => { | |
| const coordinates = []; | |
| a.geometry.coordinates.forEach((b, m) => { | |
| const target = splitIndexes[l][m]; | |
| if (target.length > 0) { | |
| const _coordinates_odd = []; | |
| const _coordinates_even = []; | |
| target.forEach((splitIndex, n) => { | |
| const sliceStart = (n === 0) ? 0 : target[n - 1]; | |
| const sliceTarget = b.slice(sliceStart, splitIndex); | |
| sliceTarget.push(sliceTarget[sliceTarget.length - 1]); | |
| if (n % 2 !== 0) _coordinates_odd.push(sliceTarget); | |
| else _coordinates_even.push(sliceTarget); | |
| if (n === target.length - 1) { | |
| const sliceTarget2 = b.slice(splitIndex, b.length); | |
| sliceTarget2.push(sliceTarget2[sliceTarget2.length - 1]); | |
| if (n % 2 !== 0) _coordinates_even.push(sliceTarget2); | |
| else _coordinates_odd.push(sliceTarget2); | |
| } | |
| }) | |
| const _coordinates = []; | |
| [_coordinates_odd, _coordinates_even.reverse()].forEach((coors, j) => { | |
| coors.forEach((coo, i) => { | |
| const thisFirst = coo[0]; | |
| const thisLast = coo[coo.length-1]; | |
| if (thisFirst[0] > 0) { | |
| _coordinates.push([[180, 90]]); | |
| _coordinates.push([[180, thisFirst[1]]]); | |
| } | |
| else { | |
| _coordinates.push([[-180, 90]]); | |
| _coordinates.push([[-180, thisFirst[1]]]); | |
| } | |
| _coordinates.push(coo); | |
| if (thisLast[0] > 0) { | |
| _coordinates.push([[180, thisLast[1]]]); | |
| _coordinates.push([[180, 90]]); | |
| } | |
| else { | |
| _coordinates.push([[-180, thisLast[1]]]); | |
| _coordinates.push([[-180, 90]]); | |
| } | |
| }) | |
| }) | |
| _coordinates.push([_coordinates[0][0]]); | |
| coordinates.push(_coordinates.flat()); | |
| } | |
| else coordinates.push(b); | |
| }) | |
| a.geometry.coordinates = coordinates; | |
| a.properties = {}; | |
| }) | |
| fs.writeFileSync('output.geojson', JSON.stringify(geojson)); |
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