I couldn't find that in the documentation, is there a built in simple way to subset an array using a boolean array for filtering? In lodash or es6
I used to use this feature in R a lot and it seemed to be quite useful. Lately I faced several use cases when I could use something like that but couldn't find out if it is supported out of the box.
something like
subset([1, 2, 3, 4, 5], [true, false, false, false, true]) // => [1, 5]
A quick way of doing this would be something like
const f = (as, bs) => as.filter((_, i) => bs[i])
f([1, 2, 3, 4, 5], [true, false, false, false, true]) // => [1, 5]
This assumes that the two arrays have the same length, which might or might not be what you want.
undefined is a falsy value. It will only include the length of the filter array.
const arr = [1, 2, 3, 4, 5];
const filter = [true, false, false, false, true];
const result = arr.filter((r, i) => filter[i]);
console.log(result);You can use built in filter array function. It has a signature which accepts an index also you can use it to filter your array as below :
How about the following?
zip=rows=>rows[0].map((_,c)=>rows.map(row=>row[c]))
zip([[1, 2, 3, 4, 5], [true, false, false, false, true]]).filter(e => e[1])
// [ [ 1, true ], [ 5, true ] ]
