Combine multidimensional array, javascript

Question

I'm trying to do something simple but it doesn't work.

I have two arrays that have a structure like this;

total ->
[0]-> [Day: 2016-04-19, Total: 23] 
[1]-> [Day: 2016-04-18, Total: 20]
failed ->
[0]-> [Day: 2016-04-19, Failed: 2] 
[1]-> [Day: 2016-04-18, Failed: 0]

I'm trying to add the "Failed" key with it's value to the "total" array but it just won't bite so the output looks something like this;

arr ->
[0]-> [Day: 2016-04-19, Total: 23, Failed: 2]
[1]-> [Day: 2016-04-18, Total: 23, Failed: 0]
...

The "total" I have assigned to var sql1 and "failed" I have assigned to var sql2 and then I've tried various functions and for loops like:

for (var i = 0; i < sql1.length; i++) {
    sql1[i][2] = sql2[i][1];
}

Yet sql1 remains the same. What am I doing wrong?

I've also tried

sql1[i].push(sql2[i][1]);

But that didn't work either.

Nina Scholz · Accepted Answer · 2016-04-20 07:55:23Z

1

You can use some loops an a hash table for the correct keys.

var data = { total: [{ Day: '2016-04-19', Total: 23 }, { Day: '2016-04-18', Total: 20 }], failed: [{ Day: '2016-04-19', Failed: 2 }, { Day: '2016-04-18', Failed: 0 }] },
    grouped = [];

Object.keys(data).forEach(function (k) {
    data[k].forEach(function (a) {
        var key = { total: 'Total', failed: 'Failed' }[k];
        if (!this[a.Day]) {
            this[a.Day] = { Day: a.Day, Total: 0, Failed: 0 };
            grouped.push(this[a.Day]);
        }
        this[a.Day][key] += a[key];
    }, this);
}, Object.create(null));

document.write('<pre>' + JSON.stringify(grouped, 0, 4) + '</pre>');

answered Apr 20, 2016 at 7:55

Nina Scholz

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1 Comment

HenrikM Over a year ago

Thanks! Worked perfectly with some minor rewriting, had to replace { Day: a.Day, Total: 0, Failed: 0 }; with { Day: a.Day, Total: '', Failed: '' }; to remove the 0 that would otherwise show up as a prefix. Thanks!

andreasonny83 · Accepted Answer · 2016-04-20 07:51:09Z

1

You can use the Array.prototype.concat() for concatenate multiple arrays in this way:

var alpha = ['a', 'b', 'c'],
numeric = [1, 2, 3];

var alphaNumeric = alpha.concat(numeric);

console.log(alphaNumeric); // Result: ['a', 'b', 'c', 1, 2, 3]

However, looking at your code it seems you're messing up arrays with Object. Your code should look more like this:

var total = [{
  Day: "2016-04-19",
  Total: 23
},
{
  Day: "2016-04-18",
  Total: 20
}];

var failed = [{
  Day: "2016-04-19",
  Total: 2
}, 
{
  Day: "2016-04-18",
  Total: 0
}]; 

console.log(total.concat(failed));

edited Apr 20, 2016 at 7:51

answered Apr 20, 2016 at 7:42

andreasonny83

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Comments

jcubic · Accepted Answer · 2016-04-20 07:53:26Z

Try this:

var total = [
    {Day: '2016-04-19', Total: 23},
    {Day: '2016-04-18', Total: 20}
  ],
  failed = [
    {Day: '2016-04-19', Failed: 2},
    {Day: '2016-04-18', Failed: 0}
  ];
// clone total array
var arr = total.slice().map(function(obj) {
  var result = {};
  result.Day = obj.Day;
  result.Total = obj.Total;
  return result;
});
for (var i=0; i<failed.length; ++i) {
  for (var j=0; j<arr.length; ++j) {
    if (failed[i].Day == arr[j].Day) {
      arr[j].Failed = failed[i].Failed;
    }
  }
}
document.body.innerHTML = '<pre>' + JSON.stringify(arr, true, 4) + '</pre>';

if Days are always in the same position in array you can simplify the code using:

for (var i=0; i<failed.length; ++i) {
  arr[i].Failed = failed[i].Failed;
}

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