PHP count # of items in an object of a given property value

Question

How can I count the number of items with the same folder_id# ?

Here's my list of items:

item_id=1, folder_id=1
item_id=2, folder_id=1
item_id=3, folder_id=2
item_id=4, folder_id=3

Here's my UPDATED code:

foreach($items as $item)
{
    if(????) //count of $item->folder_id > 1
       {
         //do something to $item->folder_id=1/$item->item_id=1
       }

       elseif(????) // cases where $item->item_id != $item->folder_id
       { 
         //do something else to $item->folder_id=1/$item->item_id=2
       }

       else
       { 
         //do something else to $item->folder_id=2/$item->item_id=3 and folder_id=3/item_id=4
       }
}

I'm interested in code that can tell me that the count for folder_id=1 is 2, the count for folder_id=2 is 1, and the count for folder_id=3 is also 1.

UPDATE: I've changed the code above to now include an elseif() because it didn't quite ask all the things I was interested in. Besides counting the # of each folder_id, I'm also interested in distinguishing cases where folder_id != item_id. This would put item_id=1, item_id=2, item_id=3/4 in their own conditional clauses and wouldn't lump item_id=1 and item_id=2 as before.

Any assistance would be greatly appreciated, thank you,

Jon · Accepted Answer · 2011-10-27 01:49:41Z

2

If you had an array of folder_ids, you could use array_count_values to provide exactly the result you need. So let's make an array like that out of an array of objects using array_map:

$callback = function($item) { return $item->folder_id; };
$result = array_count_values(array_map($callback, $items));

This will end up with $result being

array(
    1 => 2,
    2 => 1,
    3 => 1,
);

You can also write the callback inline for an one-liner, or if you are on PHP < 5.3 you can write it as a free function or alternatively using create_function.

See it in action (version for PHP < 5.3).

Update: follow up

Given $results from above, your loop would be:

foreach($results as $folder_id => $count) {
    if($count > 1) {
        // There were $count items with folder_id == $folder_id
    }
    // else blah blah
}

edited Oct 27, 2011 at 1:49

answered Oct 27, 2011 at 1:10

Jon

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2 Comments

tim peterson Over a year ago

Hi Jon, thanks for your help, can you follow up by helping me figure out how to put $result into the if() statement I'm interested in? thanks! -tim

tim peterson Over a year ago

Hi Jon, see my comment above which i will repeat here: can i add one more wrinkle? how could I distinguish between item_id=1 and item_id=2? As it stands, both would be placed in the if() statement. What if I wanted item_id=1 in the if() statement, item_id=2 in an elseif(), and item_id=3 and item_id=4 in the else{} statement. Including an && $item->folder_id==$item->item_id along with the $totals[$item... in the if() statement isn't working for me. thanks! -tim

alex · Accepted Answer · 2011-10-27 01:10:11Z

0

$totals = array();

foreach($items as $item) {
   $totals[$item->folder_id]++;
}

answered Oct 27, 2011 at 1:10

alex

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6 Comments

Iznogood Over a year ago

Very elegant way to do it but you could explain what it is that your code does.

alex Over a year ago

@Iznogood It just iterates over the $items, adding one to each member of the same name (which is $item->folder_id).

tim peterson Over a year ago

hi Alex, i'm confused on how to use $totals for each folder_id. Meaning, can I put this in the if() statement where $totals>1? thanks for your help! -tim

Iznogood Over a year ago

@alex I knew what it did but did not expect everyone to understand.

Eineki Over a year ago

@timpeterson just have another foreach: foreach($items as $item) { if ($totals[$item->folder_id]>1) {do_wathever; ...} else { do_other_things; ...}} }

|

xdazz · Accepted Answer · 2011-10-27 01:59:23Z

0

function count_items(Array $items, $folder_id) {
    return count(array_filter($items, 
        function($item) use($folder_id) {
            return $item->folder_id === $folder_id;
        }
     ));
}

answered Oct 27, 2011 at 1:59

xdazz

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Comments

Matt · Accepted Answer · 2011-10-27 03:11:26Z

0

I think this is what you are looking for.

function folder_count($items, $num)
{
    $cnt = 0;
    foreach($items as $item)
    {
        if($item->folder_id > $num)
        {
            $cnt++;
        }
    }
    return $cnt;
}

foreach ($items as $item)
{
    if (folder_count($items, 1))
    {
        //do something to $item->folder_id=1/$item->item_id=1, item_id=2
    }
    else
    { 
        //do something else to $item->folder_id=2/$item->item_id=3 and folder_id=3/item_id=4
    }
}

edited Oct 27, 2011 at 3:11

answered Oct 27, 2011 at 1:11

Matt

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5 Comments

Iznogood Over a year ago

Where is $items from in your function? This code will not work.

tim peterson Over a year ago

$items is my object which contains the item_id and folder_id properties

Matt Over a year ago

I thought it was a global variable, but I fixed the code to work fully as a function.

tim peterson Over a year ago

hi Matt, thanks for your help, can you follow up with how to integrate folder_count() into the if() statement i'm interested in? thanks! -tim

Iznogood Over a year ago

Thank you for fixing your answer.

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