D3.js rollup() method
Last Updated :
06 Apr, 2023
With the help of d3.rollup() method, we can get the reduced map from an iterable data structure having keys and values.
Syntax:
d3.rollup(iterable, reduce, ...keys)
Return value: It will return the reduced map from iterables.
Note: To execute the below examples you have to install the d3 library by using the command prompt for the following command.
npm install d3
Example 1: In this example, we can see that by using the d3.rollup() method, we are able to get the reduced map from an iterable data structure having keys and values.
Javascript
const 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: "ABC" , amount: "34.05" , date: "01/04/2016" }
]
let gfg = d3.rollup(data, g => g.length, d => d.amount);
console.log(gfg);
|
Output:
Map { '34.0' => 1, '120.11' => 1, '12.01' => 1, '34.05' => 1 }
Example 2:
Javascript
const 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: "DEF" , amount: "34.05" , date: "03/04/2020" }
]
const gfg = d3.rollup(data, g => g.length, d => d.name, d => d.date);
console.log(gfg);
|
Output:
Map {
'ABC' => Map { '11/12/2019' => 1 },
'DEF' => Map { '11/02/2020' => 1, '03/04/2020' => 1 },
'MNO' => Map { '01/04/2020' => 1 }
}
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