CODEWITHSUNDEEP
ramda.js
Rio
Rio

Reputation: 123

For duplicate values in an array, how do I use "repeat" with Ramda.js

I am trying to duplicate target:[ "a", "b", "c"] with count:[1, 2, 3]

Desirable output is ["a", "b", "b", "c", "c", "c"]

It's not working with this code :

const fn = ({ target, count }) => R.map (R.repeat (target, count))

const Data = { target : ["a", "b", "c"], count : [1, 2, 3] }

const result = fn(Data)

I am trying to find solution with Ramda.js.

Thanks.

Upvotes: 0

Views: 224

Answers (2)

Scott Sauyet
Scott Sauyet

Reputation: 50797

Another fairly simple solution:

const fn = ({target, count}) => 
  unnest (zipWith (repeat) (target, count))

const data = {
  target: ['a', 'b', 'c'], 
  count: [1, 2, 3]
}

console .log (fn (data))
<script src="//cdnjs.cloudflare.com/ajax/libs/ramda/0.27.1/ramda.min.js"></script>
<script> const {unnest, zipWith, repeat} = R                             </script>

A point-free function of target and data is easy enough:

compose (unnest, zipWith (repeat))

If they are wrapped in an object and you really want point-free, then the answer from Hitmands seems best, or a variant using this technique:

compose (unnest, apply (zipWith (repeat)), props (['target', 'count']))

Upvotes: 3

Hitmands
Hitmands

Reputation: 14179

Probably something like the following:

const fn = R.pipe(
  R.props(['target', 'count']),
  R.apply(R.zip),
  R.chain(R.apply(R.repeat)),
);
  

// ===

const data = { 
  target : ["a", "b", "c"], 
  count : [1, 2, 3],
}

console.log(
  fn(data),
);
<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.27.1/ramda.js" integrity="sha512-3sdB9mAxNh2MIo6YkY05uY1qjkywAlDfCf5u1cSotv6k9CZUSyHVf4BJSpTYgla+YHLaHG8LUpqV7MHctlYzlw==" crossorigin="anonymous"></script>

Upvotes: 1

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