如何分离数组并将其放在括号中

Question

我有一个数组(Geojson文件(，我想把它分成三个数组。有一些多极子坐标，我想把每个id的坐标连续，我想得到：

arrGeo = 
[ 
[-4.66478, 58.42441, 5127.4,-4.65982, 58.42082, 5074.7],
[-3.94815, 57.71632, 5000,-3.94812, 57.71576, 4374.1,-3.94216, 57.71541, 4283,-3.93717, 
57.71583, 5001],
[-3.93224, 57.71476, 4048,-3.93261, 57.71456, 3800.4] 
]

我试图通过使用for循环来实现这一点，但我无法将它们分开，我的意思是，对于每个ID，我需要创建单独的坐标数组。我的代码有什么问题？我该怎么解决？

这是我的代码：

positions =

[
{
"type": "Feature",
"geometry": {
"type": "GeometryCollection",
"geometries": [
{
"type": "Polygon",
"coordinates": [
[
[-4.66478, 58.42441, 5127.4],
[-4.65982, 58.42082, 5074.7],
]
]
},
]
},
"id": "kml_1"
},
{
"type": "Feature",
"geometry": {
"type": "GeometryCollection",
"geometries": [
{
"type": "Polygon",
"coordinates": [
[
[-3.94815, 57.71632, 5000],
[-3.94812, 57.71576, 4374.1],
]
]
},
{
"type": "Polygon",
"coordinates": [
[
[-3.94216, 57.71541, 4283],
[-3.93717, 57.71583, 5001],
]
]
},
]
},
"id": "kml_2"
},
{
"type": "Feature",
"geometry": {
"type": "GeometryCollection",
"geometries": [
{
"type": "Polygon",
"coordinates": [
[
[-3.93224, 57.71476, 4048],
[-3.93261, 57.71456, 3800.4],
]
]
},
]
},
"id": "kml_3"
},
];
var customMesh = new BABYLON.Mesh("custom", scene);
var customMesh2 = new BABYLON.Mesh("custom", scene);
let arrGeo = [];
let indices = [];

for (let i = 0; i < positions.length; i++) {
let fGeometry = positions[i].geometry.geometries;
console.log("i", fGeometry);
for (let j = 0; j < fGeometry.length; j++) {
console.log("j", j);
// console.log("p", fGeometry[1]);
for (let k = 0; k < 1; k++) {
for (let m = 0; m < 3; m++) {
for (let n = 0; n < 3; n++) {
let fGCoordinate = fGeometry[j].coordinates[k][m][n];
console.log("p", fGCoordinate);
arrGeo.push(fGCoordinate);
}
}
}
}
}

Answer 1

请在下面找到代码和演示链接

let final = [];
for (var i = 0, len = positions.length; i < len; i++) {
let a = [];
for (var j = 0, jlen = positions[i]["geometry"]["geometries"].length; j < jlen; j++) {

for (var k = 0, klen = positions[i]["geometry"]["geometries"][j]["coordinates"].length; k < klen; k++) {

for (l = 0, llen = positions[i]["geometry"]["geometries"][j]["coordinates"][k].length; l < llen; l++) {
a = a.concat(positions[i]["geometry"]["geometries"][j]["coordinates"][k][l]);
}
}
}
final.push(a);
}
console.log(final);

https://jsbin.com/hehurajoje/edit?js，控制台

Answer 2

为了获得更好的性能，您可以使用forEach。

let positions = [
{
type: "Feature",
geometry: {
type: "GeometryCollection",
geometries: [
{
type: "Polygon",
coordinates: [
[
[-4.66478, 58.42441, 5127.4],
[-4.65982, 58.42082, 5074.7],
],
],
},
],
},
id: "kml_1",
},
{
type: "Feature",
geometry: {
type: "GeometryCollection",
geometries: [
{
type: "Polygon",
coordinates: [
[
[-3.94815, 57.71632, 5000],
[-3.94812, 57.71576, 4374.1],
],
],
},
{
type: "Polygon",
coordinates: [
[
[-3.94216, 57.71541, 4283],
[-3.93717, 57.71583, 5001],
],
],
},
],
},
id: "kml_2",
},
{
type: "Feature",
geometry: {
type: "GeometryCollection",
geometries: [
{
type: "Polygon",
coordinates: [
[
[-3.93224, 57.71476, 4048],
[-3.93261, 57.71456, 3800.4],
],
],
},
],
},
id: "kml_3",
},
];

let newPolygons = []

const flatPositions = (arr)=>{
arr.forEach((pos)=>{
let p = []
pos?.geometry?.geometries.forEach((geometry)=>{
geometry?.coordinates.forEach(coord=>{
coord.forEach(coo=>{
p = p.concat(coo)
})
})
})
newPolygons.push(p)
})
}
flatPositions(positions)
console.log(newPolygons)

Answer 3

只需使用Array.prototype.reduce((
和Array.prototype.flat((
和Destructuring assignment

const arrGeo = positions.reduce((a,{geometry})=>
{
let item = []
for (let geo of geometry.geometries)
{
let p = geo.coordinates.reduce((t,c)=>
{
t.push(...c.flat())
return t
},[])
item.push(...p)
}
a.push(item)
return a
},[])

完整代码：

const positions = 
[ { type: 'Feature'
, geometry: 
{ type: 'GeometryCollection'
, geometries: 
[ { type: 'Polygon'
, coordinates: 
[ [ [ -4.66478, 58.42441, 5127.4] 
, [ -4.65982, 58.42082, 5074.7] 
] ] } ] } 
, id: 'kml_1'
} 
, { type: 'Feature'
, geometry: 
{ type: 'GeometryCollection'
, geometries: 
[ { type: 'Polygon'
, coordinates: 
[ [ [ -3.94815, 57.71632, 5000   ] 
, [ -3.94812, 57.71576, 4374.1 ] 
] ] } 
, { type: 'Polygon'
, coordinates: 
[ [ [ -3.94216, 57.71541, 4283] 
, [ -3.93717, 57.71583, 5001] 
] ] } ] } 
, id: 'kml_2'
} 
, { type: 'Feature'
, geometry: 
{ type: 'GeometryCollection'
, geometries: 
[ { type: 'Polygon'
, coordinates: 
[ [ [ -3.93224, 57.71476, 4048] 
, [ -3.93261, 57.71456, 3800.4] 
] ] } ] } 
, id: 'kml_3'
} ] 
const arrGeo = positions.reduce((a,{geometry})=>
{
let item = []
for( let geo of geometry.geometries )
{
let p = geo.coordinates.reduce((t,c)=>
{
t.push(...c.flat())
return t
},[])
item.push(...p)
}
a.push(item)
return a
},[])
arrGeo.forEach(el=> console.log(JSON.stringify(el)))

.as-console-wrapper { max-height: 100% !important; top: 0; }

Answer 4

我不确定，但如果我理解正确，这应该是想要的结果。我希望我对你有所帮助。

positions =
[
{
"type": "Feature",
"geometry": {
"type": "GeometryCollection",
"geometries": [
{
"type": "Polygon",
"coordinates": [
[
[-4.66478, 58.42441, 5127.4],
[-4.65982, 58.42082, 5074.7],
]
]
},
]
},
"id": "kml_1"
},
{
"type": "Feature",
"geometry": {
"type": "GeometryCollection",
"geometries": [
{
"type": "Polygon",
"coordinates": [
[
[-3.94815, 57.71632, 5000],
[-3.94812, 57.71576, 4374.1],
]
]
},
{
"type": "Polygon",
"coordinates": [
[
[-3.94216, 57.71541, 4283],
[-3.93717, 57.71583, 5001],
]
]
},
]
},
"id": "kml_2"
},
{
"type": "Feature",
"geometry": {
"type": "GeometryCollection",
"geometries": [
{
"type": "Polygon",
"coordinates": [
[
[-3.93224, 57.71476, 4048],
[-3.93261, 57.71456, 3800.4],
]
]
},
]
},
"id": "kml_3"
},
];
var arrGeo = [];
var res = [];
for (var i = 0; i < positions.length; i++) {
var x = positions[i].geometry.geometries;
var f = [];
for (var ii = 0; ii < x.length; ii++) {
var z = x[ii].coordinates[0];
var t = z.flat();
f.push(t)
}
res.push(f);
for (let ii = 0; ii < res.length; ii++) {
res[ii].flat();
}
}
for (var i = 0; i < res.length; i++) {
arrGeo.push(res[i].flat());
}
console.log(arrGeo);