How to Extract a Single Column (e.g., 'tag_name') from a Multi-Dimensional Array in PHP?

Retrieving a Single Column from a Multi-Dimensional Array

Retrieving a specific column from a multi-dimensional array can be a common task in many programming scenarios. In this case, the objective is to extract a comma-separated string of values from the "tag_name" key of an array.

To achieve this effect, we can employ the implode() function, which combines array elements into a string using a specified separator. To extract the desired values, we will first use the array_map() function to create a new array containing only the "tag_name" values.

Here's the solution using array_map():

$input = [
    [
        'tag_name' => 'google'
    ],
    [
        'tag_name' => 'technology'
    ]
];

$tagNames = array_map(function ($entry) {
    return $entry['tag_name'];
}, $input);

echo implode(', ', $tagNames); // 'google, technology'

In PHP 5.5.0 and later, we can also use the more concise array_column() function:

echo implode(', ', array_column($input, 'tag_name')); // 'google, technology'

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