geojson的属性功能按属性值在javascript中

Question

我有一个Geojson功能列表，每个功能都具有其属性中的资产ID。我想操纵Geojson，因此我只剩下每个资产ID的单个功能，每个功能的属性都添加到了功能属性中。

例如，以下Geojson具有4个功能。其中2个具有100和2的资产ID，其中2个资产ID为200： -

{
   "type":"FeatureCollection",
   "title":"map_features",
   "features":[
      {
         "type":"Feature",
         "geometry":{
            "type":"Point",
            "coordinates":[
               525408,
               162788
            ]
         },
         "properties":{
            "CASENO":"CASE29302",
            "CASE_TYPE":"litterBin",
            "ASSETID":"100",
            "DESCRIPTION":"Bin is full"
         }
      },
      {
         "type":"Feature",
         "geometry":{
            "type":"Point",
            "coordinates":[
               525408,
               162788
            ]
         },
         "properties":{
            "CASENO":"CASE56843",
            "CASE_TYPE":"litterBin",
            "ASSETID":"100",
            "NOTES":"Bin needs emptying"
         }
      },
      {
         "type":"Feature",
         "geometry":{
            "type":"Point",
            "coordinates":[
               525177,
               164509
            ]
         },
         "properties":{
            "CASENO":"CASE77112",
            "CASE_TYPE":"litterBin",
            "ASSETID":"200",
            "NOTES":"Bin cleaned"
         }
      },
      {
         "type":"Feature",
         "geometry":{
            "type":"Point",
            "coordinates":[
               525177,
               164509
            ]
         },
         "properties":{
            "CASENO":"CASE04393",
            "CASE_TYPE":"litterBin",
            "ASSETID":"200",
            "NOTES":"Bin full"
         }
      }
   ]
}

我希望仅保留资产ID 100和200的两个功能，并将属性从重复的功能中分组在一起： -

{
    "type": "FeatureCollection",
    "title": "map_features",
    "features": [
        {
            "type": "Feature",
            "geometry": {
                "type": "Point",
                "coordinates": [
                    525408,
                    162788
                ]
            },
            "properties": [
                {
                    "CASENO": "CASE29302",
                    "CASE_TYPE": "litterBin",
                    "ASSETID": "100",
                    "DESCRIPTION": "Bin is full"
                },
                {
                    "CASENO": "CASE56843",
                    "CASE_TYPE": "litterBin",
                    "ASSETID": "100",
                    "NOTES": "Bin needs emptying"
                }
            ]
        },
        {
            "type": "Feature",
            "geometry": {
                "type": "Point",
                "coordinates": [
                    525408,
                    162788
                ]
            },
            "properties": [
                {
                    "CASENO": "CASE56843",
                    "CASE_TYPE": "litterBin",
                    "ASSETID": "100",
                    "NOTES": "Bin needs emptying"
                },
                {
                    "CASENO": "CASE04393",
                    "CASE_TYPE": "litterBin",
                    "ASSETID": "200",
                    "NOTES": "Bin full"
                }
            ]
        }
    ]
}

我不确定是否有JavaScript / jQuery方法可能会有所帮助？我需要使用循环吗？

任何指针都将不胜感激。

Answer 1

如果您有信心重复的功能具有相同的几何形状，则可以使用以下方法：

1. 通过assetId将功能分组，您可以使用 map 使用降低在每个键的地方执行此操作是唯一的AssetId，该值是一个填充功能的数组。
2. 对于MAP中的每个项目，请使用几何>几何>的数组中的第一个功能，然后使用properties用数组替换功能数组仅属性。
3. 创建一个新的featurecollection，并在步骤2中解决了新功能。

请参阅下面的工作代码中的注释：

// group features by ASSETID
const assets = Array.from(
  fc.features.reduce((a, c) => {
    const id = c.properties.ASSETID;
    if (!a.has(id)) a.set(id, []); // <-- initialise each entry with an empty array
    a.get(id).push(c);             // <-- add the feature to the array for that ASSETID
    return a;
  }, new Map())                    // <-- the accumulator is a Map
);

// create new features
const newFeatures = assets.reduce((a, c) => {
  a.push({
    "type": "Feature",
    "geometry": c[1][0].geometry,  // <-- take geometry from first array entry
    "properties": c[1].map(f => f.properties) // <-- just retain the properties of the feature
  });
  return a;
}, []);

// create new feature collection
const newFc = {
   "type":"FeatureCollection",
   "title":"map_features",
   "features": newFeatures
}

// output
console.log(newFc);

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

<script>
const fc = {
   "type":"FeatureCollection",
   "title":"map_features",
   "features":[
      {
         "type":"Feature",
         "geometry":{
            "type":"Point",
            "coordinates":[
               525408,
               162788
            ]
         },
         "properties":{
            "CASENO":"CASE29302",
            "CASE_TYPE":"litterBin",
            "ASSETID":"100",
            "DESCRIPTION":"Bin is full"
         }
      },
      {
         "type":"Feature",
         "geometry":{
            "type":"Point",
            "coordinates":[
               525408,
               162788
            ]
         },
         "properties":{
            "CASENO":"CASE56843",
            "CASE_TYPE":"litterBin",
            "ASSETID":"100",
            "NOTES":"Bin needs emptying"
         }
      },
      {
         "type":"Feature",
         "geometry":{
            "type":"Point",
            "coordinates":[
               525177,
               164509
            ]
         },
         "properties":{
            "CASENO":"CASE77112",
            "CASE_TYPE":"litterBin",
            "ASSETID":"200",
            "NOTES":"Bin cleaned"
         }
      },
      {
         "type":"Feature",
         "geometry":{
            "type":"Point",
            "coordinates":[
               525177,
               164509
            ]
         },
         "properties":{
            "CASENO":"CASE04393",
            "CASE_TYPE":"litterBin",
            "ASSETID":"200",
            "NOTES":"Bin full"
         }
      }
   ]
}
</script>