How to combine multiple nested arrays in javascript?

Question

I have 2 sets of nested arrays:

var values = [[100, 87.5, 87.5, 87.5, 100, 100],
[87.5, 100, 100, 100, 87.5, 87.5],
[75, 75, 75, 75, 75, 75],
[50, 50, 50, 62.5, 62.5, 62.5],
[62.5, 62.5, 62.5, 50, 37.5, 50],
[0, 0, 0, 0, 0, 0]];

var date = [["2015", "2004", "2015", "2015", "2015", "2015"],
["2015", "2004", "2015", "2015", "2015", "2015"],
["2015", "2004", "2015", "2015", "2015", "2015"],
["2015", "2004", "2015", "2015", "2015", "2015"],
["2015", "2004", "2015", "2015", "2015", "2015"],
["2015", "2004", "2015", "2015", "2015", "2015"]];

What I'm trying to do is combine each array in Values and Date:

Get this :[100, 87.5, 87.5, 87.5, 100, 100]
Get this :["2015", "2004", "2015", "2015", "2015", "2015"]

Then combine like this:

[{y: 100, d:2015},{y:87.5, d: 2004},{y:87.5, d:2015}},{y:87.5, d:2015}},{y:100, d:2015}},{y:100, d:2015}]

example: https://jsfiddle.net/zidski/5808pgs4/3/

 var result = values.map(function (n, i) {
            return ({ y: n, d: values[i] });
        });

But the whole array gets added.

@NinaScholz - "Then combine like this" - I think the OP did. — evolutionxbox
– evolutionxbox, Commented Sep 18, 2017 at 14:27
It sounds like you need to use a flatMap style function, and maybe a reduce. reactivex.io/learnrx — evolutionxbox
– evolutionxbox, Commented Sep 18, 2017 at 14:29
The "then combine like this" isn't clear, it doesn't match up with the data in the arrays of arrays, and it's not clear how that mapping is supposed to get flattened. — T.J. Crowder
– T.J. Crowder, Commented Sep 18, 2017 at 14:31
you need two nested Array#map calls. Like grid.map((row, y) => row.map((item, x) => ... )) — Thomas
– Thomas, Commented Sep 18, 2017 at 14:32

Pranav C Balan · Accepted Answer · 2017-09-18 14:43:34Z

You need to iterate over the inner array as well.

var date = [  ["2015", "2004", "2015", "2015", "2015", "2015"],  ["2015", "2004", "2015", "2015", "2015", "2015"],  ["2015", "2004", "2015", "2015", "2015", "2015"],  ["2015", "2004", "2015", "2015", "2015", "2015"],  ["2015", "2004", "2015", "2015", "2015", "2015"],  ["2015", "2004", "2015", "2015", "2015", "2015"]];

var values = [  [100, 87.5, 87.5, 87.5, 100, 100],  [87.5, 100, 100, 100, 87.5, 87.5],  [75, 75, 75, 75, 75, 75],  [50, 50, 50, 62.5, 62.5, 62.5],  [62.5, 62.5, 62.5, 50, 37.5, 50],  [0, 0, 0, 0, 0, 0]];

var result = values
  // iterate over the values array
  .map(function(arr, i1) {
    // iterate over the inner array
    // in case you just want the first element as in your example then 
    // remove the first map method and replace `arr` with `values[0]` and `date[i1][i2]`  with `date[0][i2]` 
    return arr.map(function(n, i2) {
      // generate the required array object based on index
      return {
        y: n,
        // get the period from 2d array date using index
        periods: date[i1][i2] 
      }
    });
  });



document.getElementById("data").innerHTML = JSON.stringify(result, null, 3);

<pre id="data"></pre>

Nina Scholz · Accepted Answer · 2017-09-18 14:30:41Z

1

You could use a nested mapping for the values.

var values = [[100, 87.5, 87.5, 87.5, 100, 100], [87.5, 100, 100, 100, 87.5, 87.5], [75, 75, 75, 75, 75, 75], [50, 50, 50, 62.5, 62.5, 62.5], [62.5, 62.5, 62.5, 50, 37.5, 50], [0, 0, 0, 0, 0, 0]],
    date = [["2015", "2004", "2015", "2015", "2015", "2015"], ["2015", "2004", "2015", "2015", "2015", "2015"], ["2015", "2004", "2015", "2015", "2015", "2015"], ["2015", "2004", "2015", "2015", "2015", "2015"], ["2015", "2004", "2015", "2015", "2015", "2015"], ["2015", "2004", "2015", "2015", "2015", "2015"]],
    result = values.map(function (a, i) {
        return a.map(function (b, j) {
            return { d: date[i][j], y: b };
        });
    });
    
console.log(result);

.as-console-wrapper { max-height: 100% !important; top: 0; }

answered Sep 18, 2017 at 14:30

Nina Scholz

388k26 gold badges367 silver badges417 bronze badges

4 Comments

T.J. Crowder Over a year ago

Except that's not what the example output is. (Because as you pointed out, the example output is unclear.)

Nina Scholz Over a year ago

@T.J.Crowder, some say so, others no.

T.J. Crowder Over a year ago

(Geez, people, I woudn't downvote the answer because it's a bit speculative...)

Olian04 Over a year ago

@NinaScholz that's a nifty trick you did there with that css rule. Haven't seen that before :)

Tomer · Accepted Answer · 2017-09-18 14:40:10Z

You can flatten both of the arrays and then it's easy (assuming they are both of the same length):

var date = [["2015", "2004", "2015", "2015", "2015", "2015"],
    ["2015", "2004", "2015", "2015", "2015", "2015"],
    ["2015", "2004", "2015", "2015", "2015", "2015"],
    ["2015", "2004", "2015", "2015", "2015", "2015"],
    ["2015", "2004", "2015", "2015", "2015", "2015"],
    ["2015", "2004", "2015", "2015", "2015", "2015"]];
    
    var values = [[100, 87.5, 87.5, 87.5, 100, 100],
    [87.5, 100, 100, 100, 87.5, 87.5],
    [75, 75, 75, 75, 75, 75],
    [50, 50, 50, 62.5, 62.5, 62.5],
    [62.5, 62.5, 62.5, 50, 37.5, 50],
    [0, 0, 0, 0, 0, 0]];
    
    var flatValues = [].concat.apply([], values);
    var flatDates = [].concat.apply([], date);
    
     var result = flatValues.map(function (n, i) {
                return ({ y: n, periods: flatDates[i] });
            });
            
    
    
    document.getElementById("data").innerHTML = JSON.stringify(result);

<pre id="data"></pre>

Lucas · Accepted Answer · 2017-09-18 14:53:11Z

0

Probably what you want is this:

 //the concat will flatten the arrays.
 var result = [].concat.apply([],dates.map(function (subDates, i) {
      //Go throught the sub dates
      return subDates.map(function(date, j){
         //Create the object
         return { y: date, periods: values[i][j] };

     })
 }));

console.log(result);

//Output:
//[{"y":"2015","periods":100},{"y":"2004","periods":87.5},{"y":"2015","periods":87.5},{"y":"2015","periods":87.5},{"y":"2015","periods":100},...]

answered Sep 18, 2017 at 14:53

Lucas

1,32115 silver badges28 bronze badges

Comments

CodeHacker · Accepted Answer · 2017-09-18 14:54:11Z

0

You might need to map it 2 times...

var resultData = date.map(function(item,indexDate){
  return item.map(function(year, indexYear){
     return {y:year,d:values[indexDate][indexYear]};
   }); 
});

you might also want to flatten the array look at this plunkr

answered Sep 18, 2017 at 14:54

CodeHacker

2,1381 gold badge22 silver badges36 bronze badges

Collectives™ on Stack Overflow

How to combine multiple nested arrays in javascript?

5 Answers 5

Comments

4 Comments

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

5 Answers 5

Comments

4 Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related