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extend-geojson-properties

extend-geojson-properties

Extend properties of geojson (array of features or FeatureCollection) from separate dataset of jsons.

Installation

For node.js or with browserify

npm install extend-geojson-properties

To include in html page, download file index.js and rename to extend-geojson-properties.js

<script type="text/javascript" src="path/to/extend-geojson-properties.js"></script>

This create global variable extendGeoJSON.

Usage

This module return a function or create global function named extendGeoJSON that extends the geojson properties.

var extendGeoJSON = require('extend-geojson-properties');
extentGeoJSON( geojsons, dataSet, joinMap);
  • geojsons array of features or FeatureCollection
  • dataSet array of json objects from which properties need to be picked
  • joinMap joining rules

joinMap structure must be like:

var joinMap = { 
  geoKey: ... , 
  dataKey: ... ,
  popertyMap: ...
}
  • geoKey property key or feature id in geojson features that can be used as join key
  • dataKey key name in json data that will be used as join key i.e. has same value as of geoKey
  • propertyMap [optional] if not given extend all the keys of dataSet object (except dataKey) to geojson properties. If you want selective keys to be extended then provide array of objects of mapping among the items that need to be extend to geojson as properties
   {
     geoProperty: // string,  key path in geojson feature property name  
     dataProperty: // string, key path in dataSet object property/attributes name  
   }

Example

Here is the sample data set that I use for test also.

Original geojsons:

    var geojsons = [{
        type:'Feature',
        id: 'id1',
        geometry: {type: 'Point', coordinates: [34,50]},
        properties: { name: 'name1' }
      }, {
        type:'Feature',
        id: 'id3',
        geometry: {type: 'Point', coordinates: [10,35]},
        properties: { name: 'name3'}
      }, {
        type:'Feature',
        id: 'id2',
        geometry: {type: 'Point', coordinates: [-30,-50]},
        properties: { name: 'name2'}
      }];

Dataset containing the attributes that we want to extend to geojsons:

    var joinDataSet = [{
        attr1: 'name1',
        attr2: 'val1-2',
        attr3: {field : 'val1-3',count:23}
      }, {
        attr1: 'name2',
        attr2: 'val2-2',
        attr3: {field : 'val2-3',count:2}
      }, {
        attr1: 'name3',
        attr2: 'val3-2',
        attr3: {field : 'val3-3',count:105}
      }];

Case 1 joinMap does not contain the propertyMap

var joinMap = {
  geoKey:'properties.name', //here geoKey can be feature 'id' also  
  dataKey: 'attr1'};
extentGeoJSON(geojsons,dataSet,joinMap);

Output of case 1 Now geojsons contains the extended properties like this:

    [{
      type:'Feature',
      id: 'id1',
      geometry: {type: 'Point', coordinates: [34,50]},
      properties: {
        name: 'name1',
        attr2: 'val1-2',
        attr3: {field : 'val1-3',count:23}
      }
    }, {
      type:'Feature',
      id: 'id3',
      geometry: {type: 'Point', coordinates: [10,35]},
      properties: {
        name: 'name3',
        attr2: 'val3-2',
        attr3: {field : 'val3-3',count:105}
      }
    }, {
      type:'Feature',
      id: 'id2',
      geometry: {type: 'Point', coordinates: [-30,-50]},
      properties: {
        name: 'name2',
        attr2: 'val2-2',
        attr3: {field : 'val2-3',count:2}
      }
    }]

Case 2 joinMap contains the propertyMap

    var joinMap = {
      geoKey:'properties.name', //here geoKey can be feature 'id' also  
      dataKey: 'attr1',
      propertyMap:[{
          geoProperty: 'prop1',
          dataProperty:'attr2'
        }, {
          geoProperty: 'prop2',
          dataProperty: 'attr3.field'
        }, {
          geoProperty: 'count',
          dataProperty: 'attr3.count'
        }]
    };

extentGeoJSON(geojsons,dataSet,joinMap);

** Output of case 2** Now geojsons contains the extended properties like this:
```jsvascript 
    [{
      type:'Feature',
      id: 'id1',
      geometry: {type: 'Point', coordinates: [34,50]},
      properties: {
        name: 'name1',
        prop1: 'val1-2',
        prop2: 'val1-3',
        count: 23
      }
    }, {
      type:'Feature',
      id: 'id3',
      geometry: {type: 'Point', coordinates: [10,35]},
      properties: {
        name: 'name3',
        prop1: 'val3-2',
        prop2: 'val3-3',
        count: 105
      }
    }, {
      type:'Feature',
      id: 'id2',
      geometry: {type: 'Point', coordinates: [-30,-50]},
      properties: {
        name: 'name2',
        prop1: 'val2-2',
        prop2: 'val2-3',
        count:2
      }
    }]

License

This project is licensed under the terms of the MIT license.