How to merge two arrays using column values and find sum of another column's values?

Question

I am having two arrays with same keys from two different queries.

First query result:

Array
(
  [0] => Array
  (
      [Contribution] => 1000.00
      [P_Name] => A
  )
  [1] => Array
  (
      [Contribution] => 1500.00
      [P_Name] => B
  )
)

Second query result:

Array
(
  [0] => Array
  (
      [Contribution] => 100.00
      [P_Name] => A
  )
  [1] => Array
  (
      [Contribution] => 200.00
      [P_Name] => B
  )
)

The first array may be empty and/or the second may be empty.

I want to get the create a new array that finds the sum of Contribution values where P_Name values match, like this:

Array
(
  [0] => Array
  (
      [Contribution] => 1100.00
      [P_Name] => A
  )
  [1] => Array
  (
      [Contribution] => 1700.00
      [P_Name] => B
  )
)

I have tried array_merge():

$result1= $this->model1->getOthersTotal($date);
$result2=$this->model1->getMiscTotal($date);
$merged_result = array_merge( $result1, $result2 );

$merged_result contains:

Array (
    [0] => Array (
        [Contribution] => 1000.00
        [P_Name] => A
    )
    [1] => Array (
        [Contribution] => 1001.00
        [P_Name] => A
    )
    [2] => Array (
        [Contribution] => 69.00
        [P_Name] => B
    )
)

Answer 1

Little bit different approach

$array1 = [
    [
        'Contribution' => 10,
        'P_Name' => 'A'
    ],  
    [
        'Contribution' => 1500,
        'P_Name' => 'B'
    ]     
];
$array2 = [
    [
        'Contribution' => 200,
        'P_Name' => 'B'
    ],   
    [
        'Contribution' => 100,
        'P_Name' => 'C'
    ],   
];

$array3 = array_map(function($elem) use (&$array2){
    foreach($array2 as $i => &$a2){
        if($a2['P_Name'] == $elem['P_Name']){
            $a2['Contribution'] += $elem['Contribution'];
            return;
        }            
    }
    return $elem;
},$array1);

$array3 = array_merge(array_filter($array3),$array2);

print_r($array3);

output:

Array
(
    [0] => Array
        (
            [Contribution] => 10
            [P_Name] => A
        )

    [1] => Array
        (
            [Contribution] => 1700
            [P_Name] => B
        )

    [2] => Array
        (
            [Contribution] => 100
            [P_Name] => C
        )
)

Answer 2

Input:

$a=[['Contribution'=>1000,'P_Name'=>'A'],
    ['Contribution'=>1500,'P_Name'=>'B'],
    ['Contribution'=>2000,'P_Name'=>'C']];
$b=[['Contribution'=>100,'P_Name'=>'A'],
    ['Contribution'=>200,'P_Name'=>'B'],
    ['Contribution'=>300,'P_Name'=>'D']];

If you temporarily assign associative keys to the subarrays using array_column(), then you can leverage array_merge_recursive() to group on P_Name values, then call array_sum() to do the addition if there is more than one value to for a given P_Name.

Method #1: (Demo)

$keyed=array_merge_recursive(array_column($a,NULL,'P_Name'),array_column($b,NULL,'P_Name'));
foreach($keyed as $p_name=>$array){
    $result[]=['Contribution'=>(is_array($array['Contribution'])?array_sum($array['Contribution']):$array['Contribution']),'P_Name'=>$p_name];
}
var_export($result);

Or just do a standard merge to create one array, then loop and add as you go. Finalize the output array with array_values() to reindex the elements.

Method #2: (Demo)

foreach(array_merge($a,$b) as $array){
    if(isset($result[$array['P_Name']])){
        $result[$array['P_Name']]['Contribution']+=$array['Contribution'];
    }else{
        $result[$array['P_Name']]=$array;
    }
}
$result=array_values($result);
var_export($result);

Output: (from either method)

array (
  0 => 
  array (
    'Contribution' => 1100,
    'P_Name' => 'A',
  ),
  1 => 
  array (
    'Contribution' => 1700,
    'P_Name' => 'B',
  ),
  2 => 
  array (
    'Contribution' => 2000,
    'P_Name' => 'C',
  ),
  3 => 
  array (
    'Contribution' => 300,
    'P_Name' => 'D',
  ),
)

It is out of the scope of this question, but chances are the best approach would be to perform this grouping/addition via database query.

Answer 3

Here is a quick and dirty way to do it: Loop over both arrays, the outer loop fills the inner loop. If no match was fount, $x remails 0, and the value will be added to the inner loop. If a match is found, $x is 1 and the inner loop will break to continue the outer loop.

$a = [['a' => 10,'b' => 'g'], ['a' => 11,'b' => 'h']];
$b = [['a' => 1, 'b' => 'g'], ['a' => 2, 'b' => 'h'], ['a' => 3, 'b' => 'i']];

// now its fool proof.
function mergeData( $a, $b )
{
    if( empty( $a ) && empty( $b ) )
        return [];
    if( empty( $a ) )
        return $b;
    if( empty( $b ) )
        return $a;

    foreach( $b AS $i => $c ) {
        $x = 0;
        foreach( $a AS $ii => $d ) {
            if( $c['b'] == $d['b'] ) {
                $a[ $ii ]['a'] += $c['a'];
                $x             = 1;
                break;
            }
        }
        if( !$x )
            $a[] = $b[ $i ];
    }

    return $a;
}

Output

Array
(
    [0] => Array
        (
            [a] => 11
            [b] => g
        )

    [1] => Array
        (
            [a] => 13
            [b] => h
        )

    [2] => Array
        (
            [a] => 3
            [b] => i
        )

)

Answer 4

You can use array_reduce(), array_map(), and array_sum():

<?php

function merge(array ...$sets)
{
    /**
     * group contributions by name
     */
    $contributions = array_reduce(
        $sets,
        function (array $contributions, array $set) {
            foreach ($set as $element) {
                $name = $element['P_Name'];
                $contribution = $element['Contribution'];

                if (!array_key_exists($name, $contributions)) {
                    $contributions[$name] = [];
                }

                $contributions[$name][] = $contribution;

            }

            return $contributions;
        },
        []
    );

    /**
     * normalize the array so we remove the name as key, and return a tuple of name and contribution, with the desired
     * structure
     */
    return array_values(array_map(function (array $contribution, $name) {
        return [
            'Contribution' => array_sum($contribution),
            'P_Name' => $name,
        ];
    }, $contributions, array_keys($contributions)));
}

$a = [
    [
        'Contribution' => 1000,
        'P_Name' => 'A',
    ],
    [
        'Contribution' => 1500,
        'P_Name' => 'B',
    ],
];

$b = [
    [
        'Contribution' => 100,
        'P_Name' => 'A',
    ],
    [
        'Contribution' => 200,
        'P_Name' => 'B',
    ],
];

$merged = merge($a, $b);

var_dump($merged);

Note Because of using variadics, any number of arrays can be passed to merge(). Requires at least PHP 5.6, though.

For reference, see:

• http://php.net/manual/en/functions.arguments.php#functions.variable-arg-list
• http://php.net/manual/en/function.array-reduce.php
• http://php.net/manual/en/function.array-key-exists.php
• http://php.net/manual/en/function.array-map.php
• http://php.net/manual/en/function.array-sum.php
• http://php.net/manual/en/function.array-values.php
• http://php.net/manual/en/function.array-keys.php

For an example, see:

• https://3v4l.org/EI4Tn