Which is the best way to set an array of n dimensions from a function?
var v1 = [1,2,3];
var v2 = [[1,2],[3,4]];
// only valid for 1-dimension
function set(arr, dim, v) {
arr[dim] = v;
}
set(v1, 2, 33);
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1You want to assign ALL elements the same value? If it is n-dimensional, you need n indices to set a particular element.Sidharth Mudgal– Sidharth Mudgal2012-10-24 22:24:41 +00:00Commented Oct 24, 2012 at 22:24
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But there are multiple elements at that dimension, you need to specify which index to modify. That is with one dimension, you just need an index, with two dimensions, you need two indexes and so onRuan Mendes– Ruan Mendes2012-10-24 22:26:46 +00:00Commented Oct 24, 2012 at 22:26
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So as I said, you need n indices. For a 2d array like the example, you need 2 indices.Sidharth Mudgal– Sidharth Mudgal2012-10-24 22:27:38 +00:00Commented Oct 24, 2012 at 22:27
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yes, they could be passed into an array: set(v2, [0,2], 22), but how are passed from the parameter?user1243746– user12437462012-10-24 22:29:21 +00:00Commented Oct 24, 2012 at 22:29
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1 Answer
Your function can't work as designed it needs an index for each dimension
You'd need something like the following http://jsfiddle.net/nZmJT/1/
function setValueInArray(arr, value, index /*, index, index, ... */ ) {
var arrToSet = arr;
for (var i = 2; i < arguments.length - 1; i++) {
arrToSet = arr[arguments[i]];
}
arrToSet[arguments[i]]= value;
return arr;
}
var v1 = [1,2,3];
var v2 = [[1,2],[3,4]];
console.log( setValueInArray(v1, 0, 0) ); // [0,2,3]
console.log( setValueInArray(v2, 0, 0, 0) ); //[[0,2],[3,4]]
Please share with us why you'd like this. I can't think of code that can be generalized to work with multiple dimensions, you usually know the dimension, and just set it like...
v1[2][3] = 'anything';
Since in your case, you wouldn't know how many indexes to pass (otherwise you'd just use bracket access), the following may be a better fit
function setValueInArray(arr, value, indexes) {
var arrToSet = arr;
for (var i = 0; i < indexes.length - 1; i++) {
arrToSet = arr[indexes[i]];
}
arrToSet[indexes[i]] = value;
return arr;
}
Then you can call it passing the array of indexes which is created by some code outside of your control.
setValueInArray(v1, 0, indexes);
4 Comments
Bergi
+1, although I'd add an array-generator in the "unknown indizes" case for non-existing indizes.
Ruan Mendes
@Bergi Yes, you are right. But I'm not worried about edge cases, just guiding the OP on what needs to happen to achieve what they need, the less noise, the better, IMHO.
Bergi
@Marc: If you already have a function to initialize n-dimensional objects, you should be familiar with the used code mechanism and be able to integrate it easily.