How do I sort an Array with comma separated strings in PHP?

Question

it's my first post here, I'm a beginner and I hope you'll go easy on me. I searched for an answer, and read some semi-related questions. I've been stuck on this for a couple days and I really am very confused. Apologies if the double barrelled is a faux pas, it seemed less sensible to write this as two seperate questions. I'm new to programming and I had never heard of this website until yesterday, I hope to be a contributing part of what seems to be an awesome community.

I have an array, $newarray:

Array
(
    [2] => string1,10
    [7] => string2,15
    [10] => string3,3
    [11] => string4,7
)

I'm able to write it to a CSV file, and so far so good:

<?php
    $file = fopen("/myfile.csv","w");
    foreach ($newarray as $line)
      {
        fputcsv($file,explode(',',$line));
      }
    fclose($file);
?>

However, I'm trying to do two things.

Sorting the array by reverse order of the numerical values before writing to CSV, so I would have a CSV file as so:
```
string2,15
string1,10
string4,7
string3,3
```
Create a second file (after writing the first CSV), where the numerical values are stripped out, as so:
```
string2
string1
string4
string3
```

Can someone steer me in the right direction?

your array is Array ( 2 => 'string1,10', 7 => 'string2,15', 10 => 'string3,3', 11 => 'string4,7', ); ? — miglio
– miglio, Commented Oct 17, 2015 at 13:01

miglio · Accepted Answer · 2015-10-17 14:07:27Z

1

$arraybase = array(
    2 => 'string1,10',
    7 => 'string2,15',
    10 => 'string3,3',
    11 => 'string4,7',
);
function mapping($data){
    $array1 = array();//for first csv
    array_walk($data,function($value,$key)use(&$array1){
        $k=explode(',',$value);
        $array1[$k[1]] = $value;
    });
    krsort($array1);
    $array2 = array_map(function($value){//for second csv
        return preg_replace('/,\d+$/','',$value);
    },$array1);

    return array("csv1"=>$array1,"csv2"=>$array2);
}
$result = mapping($arraybase);
print('<pre>');print_r($result);

output:

Array
(
    [csv1] => Array
        (
            [15] => string2,15
            [10] => string1,10
            [7] => string4,7
            [3] => string3,3
        )

    [csv2] => Array
        (
            [15] => string2
            [10] => string1
            [7] => string4
            [3] => string3
        )

)

edited Oct 17, 2015 at 14:07

answered Oct 17, 2015 at 13:33

miglio

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3 Comments

jiggers Over a year ago

I tried this and it sorted by the key (11, 10, 7, 2), and not by what would be the second column in the CSV (15,10,7,3). Not sure if I'm using the correct terminology but if you try your code and compare to my question I believe you will see the difference. However, your code has helped me understand some concepts, thank you.

miglio Over a year ago

I've fixed all in a function.

jiggers Over a year ago

Thank you very much miglio, I've incorporated into my code and it works perfectly.

Jeffwa · Accepted Answer · 2015-10-17 13:03:49Z

Does your $newArray have to have concatinated values? If not, it's better to have them as sub-arrays:

$newArray = array (
    2 => array(
        0 => 'string1',
        1 => 10,
    ),
    7 => array(
        0 => 'string2',
        1 => 15,
    ),
    10 => array(
        0 => 'string3',
        1 => 3,
    ),
    11 => array(
        0 => 'string4',
        1 => 7,
    ),
);

Then you can sort using array_multisort:

$strings = array();
$numbers = array();
foreach ($newArray as $key => $row) {
    $strings[$key]  = $row[0];
    $numbers[$key] = $row[1];
}

array_multisort($numbers, SORT_DESC, $strings, SORT_ASC, $newArray);

When you write to the CSV:

<?php
    $file = fopen("/myfile.csv","w");
    foreach ($newArray as $line) {
        fputcsv($file, $line); // No need to explode as your data ia already in an array
    }
    fclose($file);
?>

To write to a second CSV with just the strings:

<?php
    reset($newArray); // Sets the pointer in the array back to the beginning so it can be looped over again
    $file = fopen("/myfile2.csv","w");
    foreach ($newArray as $line) {
        fputcsv($file, $line[0]);
    }
    fclose($file);
?>

Ulrik Pedersen · Accepted Answer · 2015-10-17 13:03:22Z

0

For your first question try http://php.net/manual/en/function.rsort.php and give it at shot :)

answered Oct 17, 2015 at 13:03

Ulrik Pedersen

731 silver badge12 bronze badges

1 Comment

mickmackusa Jan 29 at 14:15

This "answer" could have been a comment.

Professor Abronsius · Accepted Answer · 2015-10-17 14:46:21Z

0

$a=array(/* Original array */
    2   =>  'string1,10',
    7   =>  'string2,15',
    10  =>  'string4,3',
    11  =>  'string4,7'
);      

$c=array();
foreach( $a as $index => $value ){
    list($s,$i)=explode(',', $value );
    $c[$i]=$value;
}
/* Sort in reverse order */
krsort($c);

/* The value of $c is then written to your csv */

/* callback function to get the string */
function cb(&$item,$key){
    list( $s,$i )=explode(',',$item );
    $item=$s;
}
array_walk( $c, 'cb' );

echo '<pre>',print_r($b,true),'</pre>';

edited Oct 17, 2015 at 14:46

answered Oct 17, 2015 at 13:08

Professor Abronsius

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2 Comments

jiggers Over a year ago

PHP Warning: array_walk() expects parameter 1 to be array, null given in test.php on line 23. Is the output from your code as it is.

Professor Abronsius Over a year ago

Oops, I had used the wrong variable in the array_walk function - should have been $c rather than $b

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