With the help of d3.indexes() method, we can get the nested array instead of nested map having key as element. We get an object as unique values instead of an array by using this method.
Syntax :
d3.indexes(iterable, ...keys)
Return value: It returns the nested array instead of nested map.
Note: To execute the below examples you have to install the d3 library by using this command prompt we have to execute the following command.
npm install d3
Example 1: In this example we can see that by using d3.indexes() method, we are able to get the nested array instead of nested map having key as element and value as object of unique variables.
Javascript
// Defining d3 contrib variable  var d3 = require('d3');   data = [   {name: "ABC",  amount: "34.0",  date: "11/12/2015"},   {name: "DEF", amount: "120.11", date: "11/12/2015"},   {name: "MNO", amount: "12.01", date: "01/04/2016"},   {name: "XYZ", amount: "34.05", date: "01/04/2016"} ] var gfg = d3.indexes(data, d => d.name);   console.log(gfg); |
Output:
[ [ 'ABC', { name: 'ABC', amount: '34.0', date: '11/12/2015' } ],
[ 'DEF', { name: 'DEF', amount: '120.11', date: '11/12/2015' } ],
[ 'MNO', { name: 'MNO', amount: '12.01', date: '01/04/2016' } ],
[ 'XYZ', { name: 'XYZ', amount: '34.05', date: '01/04/2016' } ] ]
Example 2:
Javascript
// Defining d3 contrib variable  var d3 = require('d3');   data = [   {name: "ABC",  amount: "34.0",  date: "11/12/2019"},   {name: "DEF", amount: "120.11", date: "11/02/2020"},   {name: "MNO", amount: "12.01", date: "01/04/2020"},   {name: "XYZ", amount: "34.05", date: "03/04/2020"} ]   var gfg = d3.indexes(data, d => d.name, d => d.date); console.log(gfg); |
Output:
[ [ 'ABC', [ [Array] ] ], [ 'DEF', [ [Array] ] ], [ 'MNO', [ [Array] ] ], [ 'XYZ', [ [Array] ] ] ]
