tidyverse

tidyverse aims at easing data manipulation with javascript. It is inspired by Hadley Wickham's tidyverse R package and reproduces its API.

So far, one function is implemented:

• pivot_longer: converts an array of objects from a wider format to a longer format.
  • data: the array to pivot
  • cols: an array of field names
  • name_to: name of the added field

The returned objects will also have an added property value with the value of the pivoted fields.

Wider and Longer data table

Wider data table

In the mock data table below, years are used as column names, when they actually belong to the same dimension "year". The rows contains several values (one for each year).

name	gender	2017	2018	2019
Argentina	female	34	7	3
Armenia	female	14.6	12	19.8
Argentina	male	54	32	60
Armenia	male	43	12	25

Longer Data table

This longer data table contains the same information, but the years are stored in a unique column. The values are also stored in a newly created column "values". Each row contains a single observation.

name	gender	year	value
Argentina	female	2017	34
Armenia	female	2017	14.6
Argentina	male	2017	54
Armenia	male	2017	43
Argentina	female	2018	7
Armenia	female	2018	12
Argentina	male	2018	32
Armenia	male	2018	12
Argentina	female	2019	3
Armenia	female	2019	19.8
Argentina	male	2019	60

pivot_longer converts a data table from the wider format to the longer format.

Example

import { pivot_longer } from "tidyverse";

const wider = [
  {
    country: "Argentina",
    gender: "female",
    2015: 0.3,
    2016: 0.7,
    2017: 0.7
  },
  {
    country: "Armenia",
    gender: "female",
    2015: 7.2,
    2016: 7.7,
    2017: 7.6
  }
];

const longer = pivot_longer({
  data: wider,
  cols: [2015, 2016, 2017],
  name_to: "year"
})

console.log(longer);
// [
//   {
//     "country": "Argentina",
//     "gender": "female",
//     "year": 2015,
//     "value": 0.3
//   },
//   {
//     "country": "Armenia",
//     "gender": "female",
//     "year": 2015,
//     "value": 7.2
//   },
//   {
//     "country": "Argentina",
//     "gender": "female",
//     "year": 2016,
//     "value": 0.7
//   },
//   {
//     "country": "Armenia",
//     "gender": "female",
//     "year": 2016,
//     "value": 7.7
//   },
//   {
//     "country": "Argentina",
//     "gender": "female",
//     "year": 2017,
//     "value": 0.7
//   },
//   {
//     "country": "Armenia",
//     "gender": "female",
//     "year": 2017,
//     "value": 7.6
//   }
//  ]