Add element to existing object with index and value

Question

I would like to iterate through two arrays subtracting one arrays value from another and adding their specific difference values to an object. So for example I have:

var answer = [];
var boom = [1,2,3,4];
var other = [[1,2,3,4],
             [2,3,4,5],
             [6,7,8,9];

for(var i=0; i<other.length; i++) {
    for(var e=0; e<4; e++){
        answer[e] = boom[e] - other[i][e];
    }
}

This give me an output of:

Object {0: -5, 1: -5, 2: -5, 3: -5}

Which is boom subtracted from the last array in other what I am looking for and I think I am very close to getting it is:

Object [{0: [ 0, 0, 0, 0]},
        {1: [-1,-1,-1,-1]},
        {2: [-5,-5,-5,-5]}];

You can see that it will add the results of each iteration of the second for loop to the object answer. How can I accomplish this?

sbking · Accepted Answer · 2013-12-03 06:03:36Z

1

for(var i=0; i<other.length; i++) {
    answer[i] = [];
    for(var e=0; e<4; e++){
        answer[i][e] = boom[e] - other[i][e];
    }
}

answered Dec 3, 2013 at 6:03

sbking

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Comments

Arun P Johny · Accepted Answer · 2013-12-03 06:03:37Z

1

You need to initialize answer as an object not an as array, also you need to create a new answer array representing each set of values in other

var answer = {};
var boom = [1, 2, 3, 4];
var other = [
    [1, 2, 3, 4],
    [2, 3, 4, 5],
    [6, 7, 8, 9]
];

for (var i = 0; i < other.length; i++) {
    var temp = answer[i] = {};
    for (var e = 0; e < 4; e++) {
        temp[e] = boom[e] - other[i][e];
    }
}

Demo: Fiddle

answered Dec 3, 2013 at 6:03

Arun P Johny

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