Multi-Dimensional Array: How to build a recursive count()

Question

I have a multi-dimensional array:

membership = array(5) { 
 [0]=> array(4) { [0]=> string(21) "Group A" [1]=> string(9) "10/1/2011" [2]=> string(9) "3/31/2012" [3]=> string(8) "00004130" } 
 [1]=> array(4) { [0]=> string(22) "Group B" [1]=> string(8) "4/1/2011" [2]=> string(9) "9/30/2011" [3]=> string(8) "00005005" } 
 [2]=> array(4) { [0]=> string(22) "Group A" [1]=> string(9) "10/1/2010" [2]=> string(9) "3/31/2011" [3]=> string(8) "00004130" } 
 [3]=> array(4) { [0]=> string(22) "Group B" [1]=> string(8) "4/1/2010" [2]=> string(9) "9/30/2010" [3]=> string(8) "00005005" }  
 [4]=> array(4) { [0]=> string(22) "Group B" [1]=> string(8) "10/1/2010" [2]=> string(9) "3/31/2011" [3]=> string(8) "00005005" }  
}

I need to discover which group is in the membership array and how many times it appears.

PHP's count() does not have recursive capability, but it's output would be ideal if it did (i.e. ['Group A'] => 2 ['Group B'] => 3 ).

I thought about using the array_diff_uassoc() but, I'm just not sure. So I thought it wise to ask for some help before I wander aimlessly down the wrong path. I am sure there is more than one way, but I always find very interesting coding concepts on SO.

I'm running php 5.3.5 Thank you in advance for your suggestions and help.

PHP's count() does not have recursive capability huh? Look into manual on count's 2nd argument. Anyway it wont do what You want anyway, just simply use foreach and that's it. — Bartosz Grzybowski
– Bartosz Grzybowski, Commented Mar 19, 2012 at 5:35
Since they're all at the same depth, why do you need it to be recursive? Potential future reuse? — Rick
– Rick, Commented Mar 19, 2012 at 5:38
Re: @Bartosz and those who up count his comment; he answered his own comment with "anyway, it won't do what you want anyway.." PHP's count() only adds the number of items within a multi-dimensional array, it does not list the name and how often it shows the way it does on a single level array. It would be more beneficial to up count either of the two answers that were given that DO answer the post accurately. As oftentimes happens on SO, some like to respond right away but not with the care and knowledge of others. Please show your recognition where it's best deserved - keeping SO the best — Ricalsin
– Ricalsin, Commented Mar 20, 2012 at 19:59

Jeremy Harris · Accepted Answer · 2012-03-19 05:52:40Z

2

This should do the trick with minimal code:

$memberships = array(); // Your multi-dimensional array

foreach($memberships as $membership)
{
   $count[$membership[0]]++;
}

var_dump($count)

Sorry for the late post BTW, I wanted to test it and make sure it would work as expected.

Output is:

array(2) {
  ["Group A"]=>
  int(2)
  ["Group B"]=>
  int(3)
}

answered Mar 19, 2012 at 5:52

Jeremy Harris

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3 Comments

Ricalsin Over a year ago

Thanks! Nice, clean, simple. Thanks for taking the time!

Ricalsin Over a year ago

And thanks for the Ideone.com test results! I've seen this site coming up more in my searches. It looks interesting. Thanks.

Jeremy Harris Over a year ago

Yeah, I only started using it recently. It's very handy for testing small snippets of code to make sure a solution will actually work.

Joseph · Accepted Answer · 2012-03-19 05:50:47Z

1

given what you have, this is it. doesn't even need to be recursive since your array is just 2D

<?php
$membership = array( 
    array("Group A","10/1/2011","3/31/2012","00004130" ),
    array("Group B","4/1/2011","9/30/2011","00005005" ), 
    array("Group A","10/1/2010","3/31/2011","00004130" ), 
    array("Group B","4/1/2010","9/30/2010","00005005" ),  
    array("Group B","10/1/2010","3/31/2011","00005005" )  
);

//initialize array for safety
$count = array();

//loop through each item
foreach($membership as $row){

    //check if group exists in count array
    $group = $row[0];
    $groupExists = array_key_exists($group,$count);

    if($groupExists){
        //if we've crossed paths before, just add 1
        $count[$group]++;
    } else {
        //otherwise, let's start with 1
        $count[$group]=1;
    }
}

var_dump($count);

//output dump should look like 
array(2) {
  ["Group A"]=> int(2)
  ["Group B"]=> int(3)
}

edited Mar 19, 2012 at 5:50

answered Mar 19, 2012 at 5:45

Joseph

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1 Comment

Ricalsin Over a year ago

Thanks for taking the time, Joseph. Cillosis was just simpler, but I do appreciate the lesson in your post. Again, Thank you!

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