I want to extract a subarray from a multidimensional array and have the original array be mutated so it no longer contains the extracted subarray
If I have a multidimensional array called originalArray
I can extract a subarray from a list of header indices
function newArrCols(arrayofarray, indexlist) {
return arrayofarray.map(function (array) {
return indexlist.map(function (idx) {
return array[idx];
});
});
}
So If:
idxList = [1,2,5,7]
subArray = newArrCols(originalArray, idxList)
Know I have to delete the subArray from the originalArray
//Remove columns from original arr w.r.t headeridx
for (var i = 0; i <= idxList.length - 1; i++) {
originalArray.map(a => a.splice(idxList[i], 1));
}
Is there a way to do this in a single process I would like to skip the deleting part
Thanks
EDIT:
Create a temporary empty array that will hold the items of the originalArray that aren't included in the idxList
let tempArray = [];
Create the subArray and populate the tempArray using Array.reduce():
let subArray = originalArray.reduce((accumulator, current, index) => {
if (idxList.includes(index)) {
//if the current index is included in the idxList array,
//push the current value to the accumulator
accumulator.push(current);
} else {
//push the current value to the `tempArray`.
tempArray.push(current)
}
return accumulator;
}, []);
Replace the originalArray with a deep clone of the tempArray
originalArray = JSON.parse(JSON.stringify(tempArray));
Working snippet below.
let originalArray = [
[0, 0, 0, 0],
[1, 1, 1, 1],
[2, 2, 2, 2],
[3, 3, 3, 3],
[4, 4, 4, 4],
[5, 5, 5, 5],
[6, 6, 6, 6],
[7, 7, 7, 7],
];
let idxList = [1, 2, 5, 7];
let tempArray = [];
//Can also be written in a one line arrow function
let subArray = originalArray.reduce((a, c, i) => (idxList.includes(i) ? a.push(c) : tempArray.push(c), a), []);
originalArray = JSON.parse(JSON.stringify(tempArray));
tempArray = [];
console.log({
subArray: JSON.stringify(subArray)
});
console.log({
originalArrayAfter: JSON.stringify(originalArray)
});