Looping though arrays dealing with null values

Question

I have an array myArray

Array ([0] =>(
         Number => 02348
         Food => Array (
             [0] => orange
             [1] => apple
             [2] => plum )
         State => Array (
             [0] => california
             [1] => texas
             [2] => arizona )
        Status => good )
       [1] =>(
         Number => 34
         Food => Array (
             [0] => grape
             [1] => bannana
             [2] => tomato )
        Status => rotten )
        [2] =>(
         Number => 007
         Food => Array (
             [0] => oranges
             [1] => apples
             [2] => plums )
         State => Array (
             [0] => ohio
             [1] => utah
             [2] => vermont )
        Status => good )

I am looping though my array and then grabbing the fields i need.

for($index=0; $index < count($myArray); $index++){
   $food = array_values(array_filter($myArray[$index]["Food"]));
   $states = array_values(array_filter($myArray[$index]["State"]));

For the $states line i get an error of

Notice: Undefined index: State 
Warning: array_filter() expects parameter 1 to be array, null given

As you can see in my array State may not always be present, is there a way to get around this. Also there is a large amount of data is being pulled dynamically and it would be difficult to change the structure of the array. How can i loop though my array ignoring nulls but still keeping the place of State. For example

State => Array (
         [0] => ohio
         [1] => utah
         [2] => vermont )

would still be mapped to the [2], and not shifted to [1].

Possible duplicate of [PHP: "Notice: Undefined variable", "Notice: Undefined index", and "Notice: Undefined offset"](https://stackoverflow.com/questions/4261133/php-notice-undefined-variable-notice-undefined-index-and-notice-undef) — Qirel, Aug 02 '17 at 15:57
Fix one warning, and the other follows. Just check if the index is set before you use it. — Qirel, Aug 02 '17 at 15:57
Could you please clarify this phrase: "but still keeping the place of State".Are you probably doing something with states and food afterwards - collecting in the array or something? — Vladislav, Aug 02 '17 at 16:20
Some indexes dont exist because some are null so the value for States in this case would be 2. The value for food would be 3. — jumpman8947, Aug 02 '17 at 17:09
@Vladislav i would like to keep the array where it is for example State => Array ( [0] => ohio [1] => utah [2] => vermont ) would still be mapped to the 2nd array. — jumpman8947, Aug 02 '17 at 17:10

score 1 · Accepted Answer · answered Aug 02 '17 at 17:08

$states = array_values(array_filter($myArray[$index]["State"]));

Using the above example from your code, the array_filter function expects an array so you will need to check that the variable $myArray[$index]["State"] passed to the function is both set and also an array. This will remove the notices and warnings.

You can test for an array using the is_array() function and test if a variable is set using the isset() function.

In this example, an intermediate variable $states_array is set using data from your array. It checks if the original variable is valid, otherwise, it is set to an empty array. This is then passed into the array_filter function.

$states_array = (isset($myArray[$index]["State"]) && is_array($myArray[$index]["State"])) ? $myArray[$index]["State"] : array() ;
$states = array_values(array_filter($states_array));

You may also be interested to know that PHP 7 provides a null coalesce operator which may be helpful when handling variables that may or may not be set.

See:

http://php.net/manual/en/migration70.new-features.php#migration70.new-features.null-coalesce-op

https://lornajane.net/posts/2015/new-in-php-7-null-coalesce-operator

Looping though arrays dealing with null values

1 Answers1