Convert array of 2-tuples into one nested two elements array

Question

I am looking for the functional programming term (if it exists) of a function which converts an array of several 2-tuples into one 2-tuple array.

I think the best way to illustrate my question is through an example. I want to convert array to newArray:

const array = [[10, "A"], [20, "B"], [30, "C"], [40, "D"]]
const newArray = [[10, 20, 30, 40], ["A", "B", "C", "D"]]

My favorite language is javascript and I know I could do this through hacking with reduce but I would like to know if I can find a function like this in functional programming libraries like for example Ramda.

Thank you!

DanCouper · Accepted Answer · 2019-11-17 02:46:24Z

1

It's normally called unzip (with zip being the operation going in the other direction).

answered Nov 17, 2019 at 2:46

DanCouper

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Hitmands · Accepted Answer · 2019-11-17 08:34:42Z

0

In ramda transpose works both ways. You basically want to:

turn a list of n lists of length x, into a list of x lists of length n.

const initial = [[1, 'a'], [2, 'b'], [3, 'c']];

const result = R.transpose(initial);
console.log('result is', result);

const data = R.transpose(result);
console.log('data is', data);

<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.26.1/ramda.js" integrity="sha256-xB25ljGZ7K2VXnq087unEnoVhvTosWWtqXB4tAtZmHU=" crossorigin="anonymous"></script>

Also look at:

zip

answered Nov 17, 2019 at 8:34

Hitmands

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