Easiest way to implode() a two-dimensional array?

Question

I'm new to PHP, and don't have quite the grip on how it works. If I have a two dimensional array as such (returned by a database):

array(3) {   
    [0]=> array(1) {         
        ["tag_id"]=> string(1) "5" 
    } 
    [1]=> array(1) {         
        ["tag_id"]=> string(1) "3" 
    } 
    [2]=> array(1) {         
        ["tag_id"]=> string(1) "4" 
    } 
}

and want to turn it into the string 5,3,4 what would be the quickest way do do this? I currently have an obnoxious foreach loop, but was hoping it could be done in one line. A standard implode gives me Array,Array,Array.

What I'm trying to say is that you shouldn't care if something uses a couple of lines. — Alex Turpin, Jun 14 '12 at 17:28
@Xeon06 While I agree on principle, I'd like to see if there's a nifty way to do it better. Half of this project is learning, the other half is actual coding. (Even better, I could remove all the line breaks and tell my boss that the code only needed a one-liner) — SomeKittens, Jun 14 '12 at 17:33

Paul · Accepted Answer · 2012-06-14T18:07:51.647

33

This modifies your array using array_map, but probably for the better by turning it into a 1D array of tag_id's. Then you can just use implode like normal:

$arr = array_map(function($el){ return $el['tag_id']; }, $arr);
$str = implode(',', $arr);

If you don't want to modify your array than you can just do this:

$str = implode(',', array_map(function($el){ return $el['tag_id']; }, $arr));

Codepad Demo

edited Jun 14 '12 at 18:07

answered Jun 14 '12 at 17:30

Paul

139,544
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264

1

Well, you can actually pass the result of `array_map` right into `implode` call. ) – raina77ow Jun 14 '12 at 17:33
@raina77ow Yes, but I think it might be better to modify the original array since the extra dimension seems useless. I'll update my answer though :) – Paul Jun 14 '12 at 17:34

Bruce Lim · Answer 2 · 2015-01-07T03:18:31.203

You asked for a two-dimensional array, here's a function that will work for multidimensional array.

function implode_r($g, $p) {
    return is_array($p) ?
           implode($g, array_map(__FUNCTION__, array_fill(0, count($p), $g), $p)) : 
           $p;
}

I can flatten an array structure like so:

$multidimensional_array = array(
    'This',
    array(
        'is',
        array(
            'a',
            'test'
        ),
        array(
            'for',
            'multidimensional',
            array(
                'array'
            )
        )
    )
);

echo implode_r(',', $multidimensional_array);

The results is:

This,is,a,test,for,multidimensional,array

score 7 · Answer 3 · answered Dec 25 '16 at 06:57

7

// simplest
$str = implode(',',array_map('implode',$arr));

answered Dec 25 '16 at 06:57

Scot Nery

671
7
19

score 6 · Answer 4 · answered Jul 11 '17 at 15:48

6

If one simply wants to implode a single array "column" as in this case, then the simplest thing to do is:

implode(",", array_column($array,"tag_id"));

answered Jul 11 '17 at 15:48

apokryfos

38,771
9
70
114

Loc Nguyen · Answer 5 · 2017-02-18T10:09:14.007

3

One line command

implode(',', array_map('implode', $arr, array_fill(0, count($arr), '')))

edited Feb 18 '17 at 10:09

answered Jul 08 '16 at 07:05

Loc Nguyen

356
3
6

score 2 · Answer 6 · answered Jun 14 '12 at 17:30

Check out the below from the PHP implode() manual:

<?php
/**
 * Implode an array with the key and value pair giving
 * a glue, a separator between pairs and the array
 * to implode.
 * @param string $glue The glue between key and value
 * @param string $separator Separator between pairs
 * @param array $array The array to implode
 * @return string The imploded array
 */
function array_implode( $glue, $separator, $array ) {
    if ( ! is_array( $array ) ) return $array;
    $string = array();
    foreach ( $array as $key => $val ) {
        if ( is_array( $val ) )
            $val = implode( ',', $val );
        $string[] = "{$key}{$glue}{$val}";

    }
    return implode( $separator, $string );

}
?>

If you only want to return the value (and not the key), just modify the above to use $string[] = "{$val}";.

score 0 · Answer 7 · answered Feb 06 '16 at 15:56

function recursive_implode($connector=',', $array=[], $implod='keys'){

    if($implod=='keys'){

        $results=implode($connector,array_keys($array));
    }
    else{

        $results=implode($connector,$array);
    }

    foreach($array as $key=> $value){

        if(is_array($value)){

            $results.=$connector.recursive_implode($connector,$value,$implod);
        }
    }

    return $results;
}

Easiest way to implode() a two-dimensional array?

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