How to remove a specific index from a multidimensional array in php

Question

I am trying to remove pieces of a multidimensional array if a certain condition is met. The array can be as shown below, call it $friends:

array (size=3)
  0 => 
    array (size=1)
      0 => 
        object(stdClass)[500]
          public 'id' => int 2
          public 'first_name' => string 'Mary' (length=4)
          public 'last_name' => string 'Sweet' (length=5)
  1 => 
    array (size=1)
      0 => 
        object(stdClass)[501]
          public 'id' => int 9
          public 'first_name' => string 'Joe' (length=3)
          public 'last_name' => string 'Bob' (length=3)
  2 => 
    array (size=1)
      0 => 
        object(stdClass)[502]
          public 'id' => int 1
          public 'first_name' => string 'Shag' (length=4)
          public 'last_name' => string 'Well' (length=4)

I have a function called is_followed, that let's me see if the id of one of the people in the array is being followed by the "user". The code I am trying is:

//remove followed friends from the $friends array
$i=0;
foreach($friends as $friend) {
    foreach($friend as $f) {
        if(Fanfollow::is_followed($id,$f->id)) {
            unset($friend[$i]);
        }
    }
    $i++;
}

The $id is the id of the current user.

However, this is not working. I know that using unset on $friend and not $friends is probably the issue. But using unset on $friends also won't work, because it is the higher level array. Any ideas? Thank you.

I'm not entirely sure, but I think the problem is with 'foreach'. I believe there was something about 'foreach working with a copy' or something. Try for($i; $i < count($friend); ++$i);? — ATaylor
– ATaylor, Commented Nov 7, 2014 at 7:55

Kevin · Accepted Answer · 2014-11-07 09:00:41Z

1

If you're trying to take down the first parent keys, use the first foreach keys instead:

foreach($friends as $i => $friend) {
                //  ^ assign a key
    foreach($friend as $f) {
        if(Fanfollow::is_followed($id,$f->id)) {
            unset($friends[$i]);
            // unset this
        }
    }
}

Or if only for that single friend:

foreach($friends as $friend) {
    foreach($friend as $i => $f) {
                  //   ^ this key
        if(Fanfollow::is_followed($id,$f->id)) {
            unset($friend[$i]);
            // unset this
        }
    }
}

edited Nov 7, 2014 at 9:00

answered Nov 7, 2014 at 8:04

Kevin

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Aleksei Matiushkin · Accepted Answer · 2014-11-07 08:06:51Z

1

array_filter comes to the rescue:

array_filter($friend, 
  function($f) use($id) { return Fanfollow::is_followed($id,$f->id)); }
);

Though the solution with foreach is legit, array_filteris much more clear and sematically correct.

answered Nov 7, 2014 at 8:06

Aleksei Matiushkin

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