underscore.nest

Underscore.Nest is an extenstion for converting flat data into nested tree structures

npm install underscore.nest
2 downloads in the last week
7 downloads in the last month

Underscore.Nest

Underscore.Nest is an extenstion for converting flat data into nested tree structures. It works in Node.js and is AMD compatible.

For example, if your data looks like this:

var data = [
    { c1 : "A", c2 : "B", c3 : "C", v : 10 },
    { c1 : "A", c2 : "C", c3 : "D", v : 10 },
    { c1 : "B", c2 : "B", c3 : "C", v : 10 }
  ];

And you want it to look like this:

{
  children : [
    { name : 'A', index : 0, children : [
      { c1 : "A", c2 : "B", c3 : "C", v : 10 },
      { c1 : "A", c2 : "C", c3 : "D", v : 10 }
    ]},
    { name : 'B', index : 1, children : [
      { c1 : "B", c2 : "B", c3 : "C", v : 10 }
    ]}
  ]
}

You can accomplish that by using underscore.nest like so:

  _.nest(data, "c1");

Node.js

npm install underscore.nest

Get your favorite underscore flavor:

// get your requirements in order.
var u = require('underscore');
u.nst = require('underscore.nest');

// run your nesting
u.nst.nest(data, 'c1');

API:

Basic API:

_.nest(data, columnsToReduceBy, reduceFunction);
  • data - An array of objects
  • columnsToReduceBy - Underscore.nest can infinitly nest your data. You can either nest by a single field by passing the name of that field, or an array of fields.
  • reduceFunction - Optional. If you want to reduce your resulting children into a single value result, pass a function that takes an array of objects and returns a single value.

Note that every child grouping will recieve an index property that will mark its order in the heirarchy.

Examples:

Nest With Reduce:

If you pass in a reduce function, instead of having a children property set, you will have a value property set that will be the result of the reduce function call.


var data = [
  { c1 : "A", c2 : "B", c3 : "C", v : 10 },
  { c1 : "A", c2 : "C", c3 : "D", v : 10 },
  { c1 : "B", c2 : "B", c3 : "C", v : 10 }
];

_.nest(data, "c1", _.sum); // _.sum is from underscore.math

Results in:

{
  children : [
    { name : 'A', index : 0, value : 20 },
    { name : 'B', index : 1, value : 10 }
  ]
};

Multi Level Nesting

If you pass an array of properties instead of a single string for the second argument, nest will create a nesting based on each of those arguments like so:

var data = [
  { c1 : "A", c2 : "B", c3 : "C", v : 10 },
  { c1 : "A", c2 : "C", c3 : "D", v : 10 },
  { c1 : "B", c2 : "B", c3 : "C", v : 10 }
];

_.nest(data, ["c1", "c2"]);

Results in:

{ children :
  [
    { name : "A",
      children : [
        { name : "B",
          children :[
            { c1 : "A", c2 : "B", c3 : "C", v :10 }
          ],
          index : 0},
        { name : "C", 
          children :[
            { c1 : "A", c2 : "C", c3 : "D", v :10 }
          ],
          index : 1
        }
      ],
      index : 0 },{
      name : "B",
      index : 1,
      children : [
        { name : "B",
          index : 0
          children : [
            { c1 : "B", c2 : "B", c3 : "C", v : 10 }
          ]
      }]
    }
  ]
};

Questions?

Contact @ireneros on twitter, iros on IRC email me.

npm loves you