Delete array elements when property is of a given value

Question

I have the following array. How would I delete (unset) all elements in it for the following two scenarios?

Delete all elements where prop is equal to "a". Should delete element 0 and 2.
Delete all elements where prop is in array("a","d"). Should delete elements 0, 2, and 3.

I can obviously iterate over the array, and check if there is a match, but I expect there is a more efficient way to do so.

Array
(
    [0] => obj Object
        (
            [prop] => a
        )

    [1] => obj Object
        (
            [prop] => b
        )

    [2] => obj Object
        (
            [prop] => a
        )

    [3] => obj Object
        (
            [prop] => d
        )

)

Clément Malet · Accepted Answer · 2014-09-01 14:20:40Z

3

array_filter (PHP documentation here) is probably the best solution for that.

It will of course iterate over your array though, but it separates the iteration logic from the filtering logic, making it easier to maintain your code.

function filter_on_prop($val) {
  $arr = ['a', 'b'];
  return (!in_array($val->prop, $arr));
}

$array = array_filter ($array, 'filter_on_prop');

With an anonymous function :

$array = array_filter ($array, function ($val) use ($filter) {
  return (!in_array($val->prop, $filter));
});

$filter being your array previously selected / filled to check whatever you want.

edited Sep 1, 2014 at 14:20

answered Sep 1, 2014 at 13:50

Clément Malet

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4 Comments

user1032531 Over a year ago

Thanks Clement. Nice solution. I suppose this could also be done using an anonymous function?

user1032531 Over a year ago

I will experiment and post how it could be done with an anonymous function. Without (or with) an anonymous, is it possible to remove $arr = ['a', 'b']; from inside the function so it is more user selectable? For instance, I could run it for ['a', 'b'] as well as ['a']

Clément Malet Over a year ago

@user1032531 Yes, updated my answer according to what you want. It just depends what you want and if you're going to use your function a lot. I tend to use a callback and to include arrays (or filters) in my functions as I think it makes it easier to know WHERE I've to edit some code to change the behavior.

user1032531 Over a year ago

Perfect! I never used use before. Only thing I needed to change is function () to function ($val).

Pinoniq · Accepted Answer · 2014-09-01 13:52:01Z

0

You can use array_filter for this:

$allowedProps = array('a','d');

$myfilter = function($val) use ($allowedProps)
{
    return !in_array($val->prop, $allowedProps);
}

$myfilteredArray = array_filter($array, $myFilter);

answered Sep 1, 2014 at 13:52

Pinoniq

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1 Comment

Pinoniq Over a year ago

Looks like Clément was faster :p

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