How to get two arrays by mapping a predicate over an input array with Ramda

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Is there a concise way to achieve the same result as the below but:

without mutation

without iterating over the input array more than once

using Ramda (preferably)

I thought about using reduce to update an accumulator object containing the passed/failed arrays, but I'm not sure if there was a smarter/less verbose option

const predicate = i => i % 2 === 0;

const predicatePassed = ;

const predicateFailed = ;



[1, 2, 3, 4].forEach(i => predicate(i) ? predicatePassed.push(i) : predicateFailed.push(i))



// predicatePassed === [2, 4]

// predicateFailed === [1, 3]

asked Nov 23 '18 at 11:26

cpoliver

305

add a comment |

Is there a concise way to achieve the same result as the below but:

without mutation

without iterating over the input array more than once

using Ramda (preferably)

I thought about using reduce to update an accumulator object containing the passed/failed arrays, but I'm not sure if there was a smarter/less verbose option

const predicate = i => i % 2 === 0;

const predicatePassed = ;

const predicateFailed = ;



[1, 2, 3, 4].forEach(i => predicate(i) ? predicatePassed.push(i) : predicateFailed.push(i))



// predicatePassed === [2, 4]

// predicateFailed === [1, 3]

asked Nov 23 '18 at 11:26

cpoliver

305

add a comment |

Is there a concise way to achieve the same result as the below but:

without mutation

without iterating over the input array more than once

using Ramda (preferably)

I thought about using reduce to update an accumulator object containing the passed/failed arrays, but I'm not sure if there was a smarter/less verbose option

const predicate = i => i % 2 === 0;

const predicatePassed = ;

const predicateFailed = ;



[1, 2, 3, 4].forEach(i => predicate(i) ? predicatePassed.push(i) : predicateFailed.push(i))



// predicatePassed === [2, 4]

// predicateFailed === [1, 3]

asked Nov 23 '18 at 11:26

cpoliver

305

Is there a concise way to achieve the same result as the below but:

without mutation

without iterating over the input array more than once

using Ramda (preferably)

I thought about using reduce to update an accumulator object containing the passed/failed arrays, but I'm not sure if there was a smarter/less verbose option

const predicate = i => i % 2 === 0;

const predicatePassed = ;

const predicateFailed = ;



[1, 2, 3, 4].forEach(i => predicate(i) ? predicatePassed.push(i) : predicateFailed.push(i))



// predicatePassed === [2, 4]

// predicateFailed === [1, 3]

javascript arrays functional-programming ramda.js

asked Nov 23 '18 at 11:26

cpoliver

305

asked Nov 23 '18 at 11:26

cpoliver

305

asked Nov 23 '18 at 11:26

cpoliver

305

asked Nov 23 '18 at 11:26

cpoliver

305

asked Nov 23 '18 at 11:26

cpoliver

305

add a comment |

1 Answer
1

active

oldest

votes

You can use R.partition:

const predicate = i => i % 2 === 0;



const [predicatePassed, predicateFailed] = R.partition(predicate)([1, 2, 3, 4]);



console.log(predicatePassed);

console.log(predicateFailed);

<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.25.0/ramda.min.js"></script>

edited Nov 23 '18 at 11:47

answered Nov 23 '18 at 11:38

Ori Drori

82k148997

add a comment |

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1 Answer
1

active

oldest

votes

1 Answer
1

active

oldest

votes

You can use R.partition:

const predicate = i => i % 2 === 0;



const [predicatePassed, predicateFailed] = R.partition(predicate)([1, 2, 3, 4]);



console.log(predicatePassed);

console.log(predicateFailed);

<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.25.0/ramda.min.js"></script>

edited Nov 23 '18 at 11:47

answered Nov 23 '18 at 11:38

Ori Drori

82k148997

add a comment |

You can use R.partition:

const predicate = i => i % 2 === 0;



const [predicatePassed, predicateFailed] = R.partition(predicate)([1, 2, 3, 4]);



console.log(predicatePassed);

console.log(predicateFailed);

<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.25.0/ramda.min.js"></script>

edited Nov 23 '18 at 11:47

answered Nov 23 '18 at 11:38

Ori Drori

82k148997

add a comment |

You can use R.partition:

const predicate = i => i % 2 === 0;



const [predicatePassed, predicateFailed] = R.partition(predicate)([1, 2, 3, 4]);



console.log(predicatePassed);

console.log(predicateFailed);

<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.25.0/ramda.min.js"></script>

edited Nov 23 '18 at 11:47

answered Nov 23 '18 at 11:38

Ori Drori

82k148997

You can use R.partition:

const predicate = i => i % 2 === 0;



const [predicatePassed, predicateFailed] = R.partition(predicate)([1, 2, 3, 4]);



console.log(predicatePassed);

console.log(predicateFailed);

<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.25.0/ramda.min.js"></script>

const predicate = i => i % 2 === 0;



const [predicatePassed, predicateFailed] = R.partition(predicate)([1, 2, 3, 4]);



console.log(predicatePassed);

console.log(predicateFailed);

<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.25.0/ramda.min.js"></script>

const predicate = i => i % 2 === 0;



const [predicatePassed, predicateFailed] = R.partition(predicate)([1, 2, 3, 4]);



console.log(predicatePassed);

console.log(predicateFailed);

<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.25.0/ramda.min.js"></script>

edited Nov 23 '18 at 11:47

answered Nov 23 '18 at 11:38

Ori Drori

82k148997

edited Nov 23 '18 at 11:47

answered Nov 23 '18 at 11:38

Ori Drori

82k148997

answered Nov 23 '18 at 11:38

Ori Drori

82k148997

answered Nov 23 '18 at 11:38

Ori Drori

82k148997

add a comment |

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