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I am trying to remove the second element from every row of multidimensional array. I have only found solutions to remove the last array or to remove the last column. Here's my latest trying, but doesn't work now... Can you help me?

<?php
$array = [
    ["item_id" => "1", "item_name" => "a"],
    ["item_id" => "2", "item_name" => "b"], 
    ["item_id" => "3", "item_name" => "c"], 
    ["item_id" => "4", "item_name" => "d", "value" => "10"], 
    ["item_id" => "5", "item_name" => "e", "value" => "11"], 
    ["item_id" => "6", "item_name" => "f", "value" => "12"]
];

foreach($array AS $row)
{

 unset ($row[count($row)-2]);

}

print_r($array);
?>

My desired output is:

$array = [
    ["item_id" => "1"],
    ["item_id" => "2"], 
    ["item_id" => "3"], 
    ["item_id" => "4", "value" => "10"], 
    ["item_id" => "5", "value" => "11"], 
    ["item_id" => "6", "value" => "12"]
];
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1
  • 1
    The index of "item_name" => "a" isn't 1, it's "item_name". And it's not technically called the "second item", it's called the value with key "item_name". You access that with e.g. $array[0]["item_name"]. Please look up associative array. Commented Feb 28, 2021 at 18:13

2 Answers 2

Reset to default
4

First when you do unset ($row[count($row)-2]); you are are just unsetting an index of the $row variable which is just a copy of the value from your array. So you are not deleting the value in the array. Secondly, when you do $row[count($row)-2] you are assuming your $row has numerical indexes, which is not the case here. You want to delete the item_name index so you have to do something like unset($array[$index]['item_name']).

for($i = 0, $length = count($array); $i < $length; ++$i)
{
    unset($array[$i]['item_name']);
}
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Comments

1

An alternative to a foreach loop: array_walk() applies a user function to every item in an array:

array_walk( $arr, function(&$a){unset($a['item_name']);});
                     //    ^^^ Use reference here to 
                     //        work on the original array

For example:

$arr = [
    ["item_id" => "1", "item_name" => "a"],
    ["item_id" => "2", "item_name" => "b"], 
    ["item_id" => "3", "item_name" => "c"], 
    ["item_id" => "4", "item_name" => "d", "value" => "10"], 
    ["item_id" => "5", "item_name" => "e", "value" => "11"], 
    ["item_id" => "6", "item_name" => "f", "value" => "12"]
];

array_walk( $arr, function(&$a){unset($a['item_name']);});

print_r($arr);

/* Output

Array
(
    [0] => Array
        (    [item_id] => 1
        )
    [1] => Array
        (    [item_id] => 2
        )
    [2] => Array
        (
            [item_id] => 3
        )
    [3] => Array
        (   [item_id] => 4
            [value] => 10
        )
    [4] => Array
        (   [item_id] => 5
            [value] => 11
        )
    [5] => Array
        (   [item_id] => 6
            [value] => 12
        )
)
*/
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1 Comment

array_walk should not be used for structural changes as it can be unpredictable, as per the PHP manual: "Only the values of the array may potentially be changed; its structure cannot be altered, i.e., the programmer cannot add, unset or reorder elements. If the callback does not respect this requirement, the behavior of this function is undefined, and unpredictable." - php.net/manual/en/function.array-walk.php

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