Compare two 2d arrays & get intersection and differences

Question

I want to compare the data in whole rows between the two arrays and produce:

an array of intersecting rows and
an array where rows in the first array are not found in the second array and
an array where rows in the second array are not found in the first array.

I have two multidimensional arrays with me.

$array1 = [
    ['sight_id' => 13, 'location' => 'Jodhpur, Rajasthan, India'],
    ['sight_id' => 14, 'location' => 'Jodhpur Jn, Jodhpur, Rajasthan, India'],
    ['sight_id' => 15, 'location' => 'D-Kirtinagar, Jodhpur, Rajasthan, India'],
];

$array2 = [
    ['sight_id' => 13, 'location' => 'Jodhpur, Rajasthan, India'],
    ['sight_id' => 14, 'location' => 'Jodhpur Jn, Jodhpur, Rajasthan, India'],
    ['sight_id' => 16, 'location' => 'Jaisalmer, Rajasthan, India'],
    ['sight_id' => 17, 'location' => 'Fort Road, Amar Sagar Pol, Jaisalmer, Rajasthan, India'],
];

Desired results:

$intersect_array = [
    ['sight_id' => 13, 'location' => 'Jodhpur, Rajasthan, India'],
    ['sight_id' => 14, 'location' => 'Jodhpur Jn, Jodhpur, Rajasthan, India'],

and

$only_a1 = [
    ['sight_id' => 15, 'location' => 'D-Kirtinagar, Jodhpur, Rajasthan, India'],
]

and

$only_a2 = [
    ['sight_id' => 16, 'location' => 'Jaisalmer, Rajasthan, India'],
    ['sight_id' => 17, 'location' => 'Fort Road, Amar Sagar Pol, Jaisalmer, Rajasthan, India'],
];

For common data array I done this..function multi_array_intersect($a, $b) { return strcmp ( $a ['sight_id'], $b ['sight_id'] ); } $common_sights = array_uintersect ( $a1, $a2, 'multi_array_intersect' ); — Devi A
– Devi A, Commented Jun 1, 2016 at 9:49
Edit your question to explain what have you done to try achieving desired result. — Rohan Sanap
– Rohan Sanap, Commented Jun 1, 2016 at 10:51

David162795 · Accepted Answer · 2016-06-01 09:51:26Z

1

Convert arrays to a format, where array index is the sight_id:

$b1 =array();
foreach($a1 as $x)
    $b1[$x['sight_id']] = $x['location'];

$b2 =array();
foreach($a2 as $x)
    $b2[$x['sight_id']] = $x['location'];

Calculate the differences and intersection:

$c_intersect = array_intersect_key($b1,$b2);
$c_1 = array_diff_key($b1,$b2);
$c_2 = array_diff_key($b2,$b1);

Convert arrays back to your format:

$intersect_array = array();
foreach($c_intersect as $i=>$v)
    $intersect_array[] = array('sight_id'=>$i,'location'=>$v);

$only_a1 = array();
foreach($c_1 as $i=>$v)
    $only_a1[] = array('sight_id'=>$i,'location'=>$v);

$only_a2 = array();
foreach($c_2 as $i=>$v)
    $only_a2[] = array('sight_id'=>$i,'location'=>$v);

answered Jun 1, 2016 at 9:51

David162795

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2 Comments

Devi A Over a year ago

What if in future I have to add two more columns to that array..??

David162795 Over a year ago

Then instead of storing just $x['location'] column, store whole row $x . Then restore it simply $only_a2[] = $v

mickmackusa · Accepted Answer · 2022-02-23 11:45:10Z

It is not necessary to mutate/prepare your two-dimensional arrays in order to compare the rows. Because whole rows from one array relate to whole rows in the other array, you don't need to specify a column to compare -- just compare the full row data.

Code: (Demo) (Or with a declared function)

echo "Intersection:\n";
var_export(
    array_uintersect($array1, $array2, fn($a, $b) => $a <=> $b)
);

echo "\nUnique in first:\n";
var_export(
    array_udiff($array1, $array2, fn($a, $b) => $a <=> $b)
);

echo "\nUnique in second:\n";
var_export(
    array_udiff($array2, $array1, fn($a, $b) => $a <=> $b)
);

Output:

Intersection:
array (
  0 => 
  array (
    'sight_id' => 13,
    'location' => 'Jodhpur, Rajasthan, India',
  ),
  1 => 
  array (
    'sight_id' => 14,
    'location' => 'Jodhpur Jn, Jodhpur, Rajasthan, India',
  ),
)
Unique in first:
array (
  2 => 
  array (
    'sight_id' => 15,
    'location' => 'D-Kirtinagar, Jodhpur, Rajasthan, India',
  ),
)
Unique in second:
array (
  2 => 
  array (
    'sight_id' => 16,
    'location' => 'Jaisalmer, Rajasthan, India',
  ),
  3 => 
  array (
    'sight_id' => 17,
    'location' => 'Fort Road, Amar Sagar Pol, Jaisalmer, Rajasthan, India',
  ),
)

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