extend-geojson-properties

extend-geojson-properties

Extend properties of geojson objects 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,   //array of features
  dataSet,    // array of json objects
  joinMap     // joining rules
);

joinMap structure must be like:

var joinMap = {
  geoKey:  // property key or feature id that can be used as join key  
  dataKey:  // key name json data that will be used as join key 
            // i.e. has same values as of geoKey
  propertyMap:[  // array of mapping among the  items that need to be extend 
                 // to geojson as properties
    {
      geoProperty: 'prop1' // output geojson will have property by 'prop1' name 
      dataProperty:'attr2' // json property that needs to be extended to geojson 
        // in this case property name 'attr2'    
    }, 
    //many more rules can be added
    {
      geoProperty: ,
      dataProperty: 
    },  
    ... 
  ]
};

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}
      }];

Joining rules or joinMap:

    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'
        }]
    };

Once we have set properly the joinMap the function is very simple :

extentGeoJSON(geojsons,dataSet,joinMap);

Now geojsons contains the extended properties:

    [{
      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.