如何合并一组 geojson 项目的坐标值？

Question

您好，我正在处理一个大型 geojson 数据集，我正在尝试查看是否可以根据共享相同“User_ID”的条目合并每个条目的坐标值。

我的数据集如下所示：

{
     "geometry":{
        "type":"Point",
        "coordinates":[
           -3.231658,
           51.687026
        ]
     },
     "type":"Feature",
     "properties":{
        "User_ID":1002848324
     }
  },
  {
     "geometry":{
        "type":"Point",
        "coordinates":[
           -3.231659,
           51.687016
        ]
     },
     "type":"Feature",
     "properties":{
        "User_ID":1002848324
     }
  }

我尝试使用 mwarren 的回答 url 中显示的方法合并条目：“

然而，这会带来一个小问题，即当我尝试运行测试时，“attr”被视为“意外标识符”。

目前我对代码的测试如下：

features.map(function(feature){
var matchedArray = features2.filter(function(feature2){
    return feature2.User_ID === feature.User_ID;
});
   if(matchedArray && matchedArray[0]){
      for(var attr in matchedArray[0].properties){
          feature.properties[attr] = matchedArray[0].properties[attr];
    }
  }
});

所需的结果应如下所示：

{
     "geometry":{
        "type":"Point",
        "coordinates":[
           -3.231658,
           51.687026
        ], [
           -3.231659,
           51.687016
        ]
     },
     "type":"Feature",
     "properties":{
        "User_ID":1002848324
     }

任何帮助将不胜感激。

Answer 1

您将 var 拼写为“war”，需要 'var'。如果这不是错误，请说明什么是 'features2' 数组。

Answer 2

从上面的评论...

"The OP needs to group/collect the data not only by same User_ID values but by both same type AND same User_ID values"

...甚至可能是相同的 geometry.type。仅基于 User_ID 的 grouping/collecting 不够明确，因为具有相同 User_ID 值的项目可能具有不同的 type 值，甚至可能在 geometry.type 值上有所不同。

一个基于 reduce 的任务，它使用一个 collector 对象，该对象以一个对象为 lookup 和一个 result 数组作为聚合的最终数据，确实解决了 OP 的任务在一个迭代步骤内...

function collectSameGeoCategoryItems(collector, item) {
  const { lookup, result } = collector;
  const { properties: { User_ID }, type } = item;

  const groupKey = `${ type }_${ User_ID }`;
  let groupItem = lookup[groupKey];

  if (groupItem) {
    // push coordinates copy into existing array of coordinate arrays.

    groupItem.geometry.coordinates.push([...item.geometry.coordinates]);
  } else {
    // create full copy of geo item in order
    // to not mutate the original reference.

    groupItem = lookup[groupKey] = {
      geometry: {
        type: item.geometry.type,
        coordinates: [ [...item.geometry.coordinates] ],
      },
      type,
      properties: { User_ID },
    };
    result.push(groupItem);
  }
  return collector;
}

const sampleData = [{
  geometry: {
    type: "Point",
    coordinates: [
      -3.231658,
      51.687026,
    ],
  },
  type: "Feature",
  properties: {
    User_ID: 1002848324,
  },
}, {
  geometry: {
    type: "Point",
    coordinates: [
      -3.231659,
      51.687016,
    ],
  },
  type: "Feature",
  properties: {
    User_ID: 1002848324,
  },
}, {
  geometry: {
    type: "Point",
    coordinates: [
      -3.231658,
      51.687026,
    ],
  },
  type: "Foo",
  properties: {
    User_ID: 1002848324,
  },
}, {
  geometry: {
    type: "Point",
    coordinates: [
      -3.231659,
      51.687016,
    ],
  },
  type: "Bar",
  properties: {
    User_ID: 1002848324,
  },
}, {
  geometry: {
    type: "Point",
    coordinates: [
      -3.231658,
      51.687026,
    ],
  },
  type: "Foo",
  properties: {
    User_ID: 1000000000,
  },
}, {
  geometry: {
    type: "Point",
    coordinates: [
      -3.231659,
      51.687016,
    ],
  },
  type: "Bar",
  properties: {
    User_ID: 1002848324,
  },
}];

console.log(
  'aggregated `result` ...',
  sampleData.reduce(collectSameGeoCategoryItems, { lookup: {}, result: [] }).result
);
console.log('unmutated sample data ... ', { sampleData });

console.log(
  'aggregated `lookup`, not needed, just for demonstration purpose ...',
  sampleData.reduce(collectSameGeoCategoryItems, { lookup: {}, result: [] }).lookup
);

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

如何合并一组 geojson 项目的坐标值？

How does one merge coordinate values of an array of geojson items?

javascript

arrays

reduce

merge

geojson