PHP: Better way to replace string value in array with an array?

Question

I'm new to PHP so I'm not sure how to optimize this code.

I execute a Python script from PHP and the $output variable returned is an array of arrays.

exec (" /Users/$USER/anaconda/bin/python /Applications/MAMP/cgi-bin/Evaluation1.py",$output)

Each array within the $output array contains one string value separated by commas. So $output is Array ( [0] => 1, 好, 0 [1] => 2, 妈妈, 3), etc.

In each array within the $output array, I use explode on the string value to create an array, and add it to my new $output array called $output2

$output2 = array();
foreach($output as $value){
$myArray = explode(',', $value);
$output2[] = $myArray;
}

Is there a way to just replace/overwrite the string value in the arrays within $output with the new array, instead of adding each item to a new $output2 array?

Jonathan Kuhn · Accepted Answer · 2014-09-16 20:18:21Z

2

You could use array_walk to do the loop over output. You pass in a callback function that is called for each value by reference so any changes to the passed in value stick to the array.

Test data:

$output = array(
    '1,A,2',
    '2,B,3',
    '3,C,4'
);

PHP >= 5.3.0

array_walk($output, function(&$val){ $val = explode(',', $val); } );

Older PHP

function mySplit(&$val){
    $val = explode(',', $val);
}
array_walk($output, 'mySplit');

Both output:

Array
(
    [0] => Array
        (
            [0] => 1
            [1] => A
            [2] => 2
        )

    [1] => Array
        (
            [0] => 2
            [1] => B
            [2] => 3
        )

    [2] => Array
        (
            [0] => 3
            [1] => C
            [2] => 4
        )

)

answered Sep 16, 2014 at 20:18

Jonathan Kuhn

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Comments

michael.schuett · Accepted Answer · 2014-09-16 20:19:28Z

1

Some great answers already. Just adding this for completeness.

$ar = array(
    "1,2,3",
    "4,5,6"
);

foreach($ar as $k => $v) {
    $ar[$k] = explode(',', $v);
}

Wold be interesting to see a a performance difference of the different methods although i doubt it would be much.

answered Sep 16, 2014 at 20:19

michael.schuett

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2 Comments

Jonathan Kuhn Over a year ago

I was actually curious about the benchmarks also so I wrote/ran a little test. Over 1000 iterations, my code with anonymous function: 32.21ms, my code with defined function:27.76ms, your code: 21.27ms, derp's code: 28.17ms. You can click on the links to see each test. While they are all close together and the difference is negligible, I think it is interesting that the anony function does offer a little overhead with your foreach winning.

michael.schuett Over a year ago

@JonathanKuhn awesome! thanks for running the tests.

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