How to count all values in a multidimensional array?

Question

I have tried solutions to many similar questions, but they all seem to give me a count for each array. So I have the following array:

Array
(
    [1] => Array
        (
            [0] => 1
            [1] => 12
            [2] => 2
        )

    [2] => Array
        (
            [0] => 1
            [1] => 13
            [2] => 3
        )

    [3] => Array
        (
            [0] => 1
            [1] => 12
            [2] => 2
        )

    [4] => Array
        (
            [0] => 1
        )

    [5] => Array
        (
            [0] => 1
        )

)

I am trying to count the duplicates across all arrays. So the output should show:

Five 1's
Two 12's
One 13
Two 2's

At the moment I am trying:

foreach($data as $key => $row) {
    print_r(array_count_values($row));
}

Which outputs the counts for each individual array

Array
(
    [1] => 1
    [12] => 1
    [2] => 1
)
Array
(
    [1] => 1
    [13] => 1
    [3] => 1
)
Array
(
    [1] => 1
    [12] => 1
    [2] => 1
)
Array
(
    [1] => 1
)
Array
(
    [1] => 1
)

I have also tried this:

foreach ($data as $key => $row) {
    $counts = array_count_values(array_column($data, $key));
    var_dump($counts);
}

Which seems to miss a lot of information, like the count of the 1's

array(2) {
  [12]=>
  int(2)
  [13]=>
  int(1)
}
array(2) {
  [2]=>
  int(2)
  [3]=>
  int(1)
}
array(0) {
}
array(0) {
}
array(0) {
}

As a note, the initial array keys will not always be sequential, as this represents a row number. So this array may contain rows 1, 2, 5, 6, 7 etc.

How would I go about counting all duplicates together?

please always post array data from var_export() calls to help volunteers to support you faster. — mickmackusa
– mickmackusa ♦, Commented Oct 13, 2018 at 22:34
Thank you, will do going forward, didn't know about this functions — katie hudson
– katie hudson, Commented Oct 13, 2018 at 22:37

mickmackusa · Accepted Answer · 2018-10-13 22:58:00Z

4

Since your array is not flattened, you will need to visit each value and increment unless you want to call merging functions.

Code: (Demo)

$array = [
    1 => [1, 12, 2],
    2 => [1, 13, 3],
    3 => [1, 12, 2],
    4 => [1],
    5 => [1]
];

//           make the generated value available outside of function scope
//           \-------------------------------v--------------------------/
array_walk_recursive($array, function($v)use(&$output) {  // visit each leafnode
    if (isset($output[$v])) {  // check if the key has occurred before
        ++$output[$v];         // increment
    } else {
        $output[$v] = 1;       // declare as 1 on first occurrence
    }
});

var_export($output);

Output:

array (
  1 => 5,
  12 => 2,
  2 => 2,
  13 => 1,
  3 => 1,
)

Or, non-recursively:

foreach ($array as $row) {
    foreach ($row as $v) {
        if (isset($output[$v])) { // check if the key has occurred before
            ++$output[$v];        // increment
        } else {
            $output[$v] = 1;      // declare as 1 on first occurrence
        }
    }
}

Or, a functional one-liner to flatten then count:

var_export(array_count_values(array_reduce($array, 'array_merge', array())));

Or, a functional one-liner with the splat operator to flatten then count:

var_export(array_count_values(array_merge(...$array)));

edited Oct 13, 2018 at 22:58

answered Oct 13, 2018 at 22:39

mickmackusa♦

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1 Comment

katie hudson Over a year ago

I think this idea works better for my situation, thanks

msg · Accepted Answer · 2018-10-13 23:03:27Z

2

You can do this quite easily by using an accumulator array and iterating all the elements:

$result = [];
foreach ($data as $row) {
    foreach($row as $value) {
        $result[$value] = isset($result[$value]) ? $result[$value] + 1 : 1;
    }
}
var_dump($result);

edited Oct 13, 2018 at 23:03

answered Oct 13, 2018 at 22:33

msg

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3 Comments

katie hudson Over a year ago

Wow, think I was trying to think too hard! Thanks

mickmackusa Over a year ago

Definitely avoid posting code that generates Notices. (people will copy-paste this stuff)

mickmackusa Over a year ago

Please don't assume that the researchers have a certain level of development skill. Always post your best code. If you know there is a better way to code something, always post that. This will help to make this site more valuable and help you to earn more points in the long run.

Nick · Accepted Answer · 2018-10-13 22:43:15Z

1

You can use call_user_func_array to merge all the individual arrays, and then array_count_values on that result:

$data = array
(array(1, 12, 2),
 array(1, 13, 3),
 array(1, 12, 2),
 array(1),
 array(1)
 );

print_r(array_count_values(call_user_func_array('array_merge', $data)));

Output:

Array
(
    [1] => 5
    [12] => 2
    [2] => 2
    [13] => 1
    [3] => 1
)

edited Oct 13, 2018 at 22:43

answered Oct 13, 2018 at 22:42

Nick

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1 Comment

mickmackusa Over a year ago

Flattening first is a good idea too. I was just about to add this to my list of solutions.

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