I would like to know how many element of each number is in array, i. e.:
[2,2,3,6,1,1001,2] should return 2 => 3, 3 => 1, 6 = >1, 1 => 1, 1001 => 1. But when I use additional array when I set counted[2] = 3, and counted[1001] = 1 I create 1002 length array (in opposite to arrays in PHP I think...). How could I improve it? (of course I don't know how many element there will be in my input array)
Thanks in advice.
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4 Answers
Use a Javascript object as a hashtable, so the numbers are represented as properties on that object:
var array = [2,2,3,6,1,1001,2];
var numbers = {};
for (var i = 0; i < array.length; i++) {
var number = array[i];
if (typeof(numbers[number]) === "undefined") {
numbers[number] = 1;
} else {
numbers[number]++;
}
}
1 Comment
josh
Nice, I was praying for that simple solution!
You could use objects.
Here is an example:
var src = [2,2,3,6,1,1001,2]
var results = {}
for (var i = 0, n = src.length; i < n; i++)
{
results[src[i]] = results[src[i]] || 0
results[src[i]] += 1
}
// Iterate over results or access by index to see frequency
for (var idx in results)
{
console.log(idx + " ==> " + results[idx])
}
Comments
Try using Object instead of Array.
Array assumes that if you insert an element at index x, then it implies that you want an array of at least x length.
