To transform arrays in JS

Question

Help, please.

How is it possible in JS to transform these arrays:

$ar1 = array('Shop 1', 15, 25, 30);
$ar2 = array('Shop 2', 25, 45, 50);
$ar3 = array('Month', 1, 2, 3);

to this:

$values = array(
   array('Month', 'Shop 1', 'Shop 2'),
   array('1', 15, 25),
   array('2', 25, 45),
   array('3', 30, 50),
);

in PHP I can do it as follow:

$result = array_map(function($a,$b,$c){ return [$a,$b,$c]; }, $ar3,$ar1,$ar2);

or like that:

function flip($arr) {
$result = array();
foreach ($arr as $index => $list) {
    foreach ($list as $key => $value) {
        $result[$key][$index] = $value;
    }
}
return $result;
}

$values = flip([$ar3, $ar1, $ar2]);

Possible duplicate of Convert array of rows to array of columns — Syed Waqas Bukhary
– Syed Waqas Bukhary, Commented Apr 8, 2017 at 13:04

Barmar · Accepted Answer · 2017-04-08 07:45:15Z

0

You can use Array.prototype.map in Javascript. It passes the array index as an argument to the callback, which you can then use to access the other two arrays.

var arr1 = ['Shop 1', 15, 25, 30];
var arr2 = ['Shop 2', 25, 45, 50];
var arr3 = ['Month', 1, 2, 3];

var result = arr3.map(function(element, index) {
  return [element, arr1[index], arr2[index]];
});

console.log(result);

answered Apr 8, 2017 at 7:45

Barmar

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Comments

Christos · Accepted Answer · 2017-04-08 07:30:10Z

0

You could try something like this:

var arr1 = ['Shop 1', 15, 25, 30];
var arr2 = ['Shop 2', 25, 45, 50];
var arr3 = ['Month', 1, 2, 3];

var res = [];
Object.keys(arr3)
      .forEach(function(key){
          res.push([arr3[key].toString(), arr1[key], arr2[key]]); 
});

console.log(res);

answered Apr 8, 2017 at 7:30

Christos

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Comments

Nina Scholz · Accepted Answer · 2017-04-08 07:30:36Z

0

With proper arrays, you could transform the single arrays with a nested loop for the result.

var array1 = ['Shop 1', 15, 25, 30],
    array2 = ['Shop 2', 25, 45, 50],
    array3 = ['Month', 1, 2, 3],
    result = [array3, array1, array2].reduce(function (r, a, i) {
        a.forEach(function (b, j) {
            r[j] = r[j] || [];
            r[j][i] = b;
        });
        return r;
    }, []);

console.log(result)

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

answered Apr 8, 2017 at 7:30

Nina Scholz

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