拆分具有特定块大小的数组

Question

For example I have a chunks array, this array has the sizes of individual chunks.

let example = [3,3]; // Chunks array
let auxarrayindex = [1,2,3,4,5,6]; // Array that I want to splice
let example2 = [3,2,3]; // Chunks array
let auxarrayindex2 = [1,2,3,4,5,6,7,8]; // Array that I want to splice

The result that I want is:

[1,2,3],[4,5,6] and the second [1,2,3],[4,5],[6,7,8]

This is my code:

for (let auxexample = 0; auxexample < example.length; auxexample++) {
    finalauxarray.push(auxarrayindex.slice(0, example[auxexample]));
}

The result from my code is:

[1,2,3],[1,2,3] and the second [1,2,3],[1,2],[1,2,3]

Answer 1

The problem is that your slice always starts at the same index (0).

Use a variable (like i ) that you increase as you take chunks:

 let example = [3,2,3]; let auxarrayindex = [1,2,3,4,5,6,7,8]; let finalauxarray = []; let i = 0; for (let auxexample = 0; auxexample < example.length; auxexample++) { finalauxarray.push(auxarrayindex.slice(i, i+=example[auxexample])); } console.log(finalauxarray);

You could also use map for your loop:

 let example = [3,2,3]; let auxarrayindex = [1,2,3,4,5,6,7,8]; let i = 0; let finalauxarray = example.map(size => auxarrayindex.slice(i, i+=size)); console.log(finalauxarray);

Answer 2

The problem is because of the slice parameters are wrong You can learn more about how slice works on this link

https://www.w3schools.com/jsref/jsref_slice_array.asp

It takes as first parameter the starti g position and as last parameter the ending position which is not included in the result

You can aslo use splice for this as well https://www.w3schools.com/jsref/jsref_splice.asp

Hope that helps

Answer 3

Working example using splice instead of slice as I think it offers a slightly cleaner API for this particular use-case:

 let example = [3, 3]; let auxArrayIndex = [1, 2, 3, 4, 5, 6]; let example2 = [3, 2, 3]; let auxArrayIndex2 = [1, 2, 3, 4, 5, 6, 7, 8]; function getChunks(chunkSizes, array) { let result = []; for (let chunkSize of chunkSizes) { result.push(array.splice(0, chunkSize)); } return result; } let chunks = getChunks(example, auxArrayIndex); let chunks2 = getChunks(example2, auxArrayIndex2); console.log(chunks); // logs "[1,2,3], [4,5,6]" console.log(chunks2); // logs "[1,2,3], [4,5], [6,7,8]"