I have an array of arrays with data like:
[[0,1],[0,2],[0,3],[1,1]]
What I want is an object that looks like: {0: [1,2,3], 1: [1]}
I tried:
var obj = {};
$.each(List, function(index, value) {
obj[value[0]] = value[2];
});
But it obviously overwrites the previous value for the key. Is there an easy way to add all the values to each unique key (sort of like a dictionary)?
This tests to see if the property exists. If not, it creates it and assigns the Array.
Once the property and array exist, it can push in the value.
var obj = {};
$.each(List, function(index, value) {
if( !obj[value[0]] )
obj[value[0]] = [];
obj[value[0]].push(value[1]);
});
You can avoid a .push() call when the Array is created if you do this...
var obj = {};
$.each(List, function(index, value) {
if( !obj[value[0]] )
obj[value[0]] = [value[1]];
else
obj[value[0]].push(value[1]);
});
And keep in mind that if you need to guarantee order of iteration, you should use an Array instead of an Object.
var arr = [];
$.each(List, function(index, value) {
if( !arr[value[0]] )
arr[value[0]] = [value[1]];
else
arr[value[0]].push(value[1]);
});