Asked  7 Months ago    Answers:  5   Viewed   35 times

I have an array:

$a = array('foo' => 'fooMe');

and I do:

print_r($a);

which prints:

Array ( [foo] => printme )

Is there a function, so when doing:

needed_function('    Array ( [foo] => printme )');

I will get the array array('foo' => 'fooMe'); back?

 Answers

29

I actually wrote a function that parses a "stringed array" into an actual array. Obviously, it's somewhat hacky and whatnot, but it works on my testcase. Here's a link to a functioning prototype at http://codepad.org/idlXdij3.

I'll post the code inline too, for those people that don't feel like clicking on the link:

<?php
     /**
      * @author ninetwozero
      */
?>
<?php
    //The array we begin with
    $start_array = array('foo' => 'bar', 'bar' => 'foo', 'foobar' => 'barfoo');

    //Convert the array to a string
    $array_string = print_r($start_array, true);

    //Get the new array
    $end_array = text_to_array($array_string);

    //Output the array!
    print_r($end_array);

    function text_to_array($str) {

        //Initialize arrays
        $keys = array();
        $values = array();
        $output = array();

        //Is it an array?
        if( substr($str, 0, 5) == 'Array' ) {

            //Let's parse it (hopefully it won't clash)
            $array_contents = substr($str, 7, -2);
            $array_contents = str_replace(array('[', ']', '=>'), array('#!#', '#?#', ''), $array_contents);
            $array_fields = explode("#!#", $array_contents);

            //For each array-field, we need to explode on the delimiters I've set and make it look funny.
            for($i = 0; $i < count($array_fields); $i++ ) {

                //First run is glitched, so let's pass on that one.
                if( $i != 0 ) {

                    $bits = explode('#?#', $array_fields[$i]);
                    if( $bits[0] != '' ) $output[$bits[0]] = $bits[1];

                }
            }

            //Return the output.
            return $output;

        } else {

            //Duh, not an array.
            echo 'The given parameter is not an array.';
            return null;
        }

    }
?>
Wednesday, March 31, 2021
 
SkyNet
answered 7 Months ago
13

Newer versions of PHP allow using array_map() with a function expression instead of a function name:

$arr2 = array_map(function($person) {
    return $person['name'];
}, $arr1);

But if you are using a PHP < 5.3, it is much easier to use a simple loop, since array_map() would require to define a (probably global) function for this simple operation.

$arr2 = array();

foreach ($arr1 as $person) {
    $arr2[] = $person['name'];
}

// $arr2 now contains all names
Wednesday, March 31, 2021
 
dmp
answered 7 Months ago
dmp
29

Based on your given code, we can reverse-engineer the structure of $arr2 to (assuming R, G and B are integer from 0 to 255):

$arr2 = array(
   0 => array(
      0 => array(
        "R" => 128,
        "G" => 64,
        "B" => 255
      ),
      1 => array(
        ...
      ) 
   )
);

Given that your $SIZE is set to 256, you will have a total of 256*256=65536 arrays further containing arrays with key-values for R, G and B, resulting in total of 256*256*3=196608 integers in 3 levels of hierarchy. No surprise your code is slow!

I think the best strategy here is to try to reduce the total number of items in your array.

Given that instead of encoding single cells as "R, G, B" triples, you could encode all values in a single integer. Such as instead of:

0 => array( "R" => $r, "G" => $g, "B" => $b )

Given that 0<=r,g,b<=255, you could encode $arr2 as:

0 => ($r<<16 + $g<<8 + $b);

Now of course you need to unpack the color value inside your loop as well. This can be achieved by:

$col = $arr2[$y][$x];
$col_b = ($col&255);
$col_g = ($col>>8)&255;
$col_r = ($col>>16)&255;
$r .= $col_r.":";
$g .= $col_g.":";
$b .= $col_b.":";

This modification alone would cut one level of hierarchy from your array completely.

While running your original code with $SIZE=256, my average execution speed in my settings was 0.30 secs. With the given refactoring, I was able to reduce this to 0.10 secs cutting your calculation time to 1/3 of the original.

You will still have a lot of work to do if you wish to improve the performance, but I hope this gives you an idea on how you could proceed.

Saturday, May 29, 2021
 
drowneath
answered 5 Months ago
44
$variable = array(3) { 
        [0]=> array(2) { 
                        [0]=> string(3) "ABC" 
                        [1]=> string(3) "744" } 
        [1]=> array(2) { 
                         [0]=> string(3) "DEF" 
                         [1]=> string(2) "86" } 
        [2]=> array(2) { 
                         [0]=> string(3) "GHI" 
                         [1]=> string(1) "2"  }
    } 

foreach($variable as $key=>$arrayStrings)
    foreach($arrayStrings as $innerKey=>$string)
           if(is_numeric($string))
              $variable[$key][$innerKey] = intval($string);
Saturday, May 29, 2021
 
LOKESH
answered 5 Months ago
63

You did not create an array. What you did was Command Substitution which would simply put the output of a command into a variable.

In order to create an array, say:

temp_list=( $(grep "[a-z]" failedfiles.txt) )

You might also want to refer to Guide on Arrays.

Thursday, September 23, 2021
 
1.21 gigawatts
answered 1 Month ago
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