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up vote 1 down vote favorite

How can I sort an array by a value from an exploded string?

To make it a bit more clear, I have data stored in a textfile in the following format:

Value_1|Value_2|Value_3|Value_4|Value_5
Value_1|Value_2|Value_3|Value_4|Value_5
Value_1|Value_2|Value_3|Value_4|Value_5
...

I read the data using

$data_file = 'foo.txt';
$lines = file($data_file, FILE_IGNORE_NEW_LINES);

then explode each line and output the content (HTML stripped to keep it clean)

foreach ($lines as $line_num => $dataset) {
  $dataset = explode('|', $dataset);
  //echo exploded values + some HTML
}

However, before I output the data, I want to sort the array by Value_2 (which is always a number) from e.g. high to low. Do I have to set the keys of the array to Value_2 and then sort it? How can I do that? What would be the best solution here?

Thanks for your help!

This is the final, slightly modified snippet for everyone who's interested:

$data_file = 'foo.txt';
$lines = file($data_file, FILE_IGNORE_NEW_LINES);

function sort_data_array($a, $b){
    $ex_a = explode('|', $a);
    $ex_b = explode('|', $b);
    if ($ex_a[1] == $ex_b[1]) {return 0;}
    return ($ex_a[1] > $ex_b[1]) ? -1 : 1;
}

uasort($lines, 'sort_data_array');
$lines = array_values($lines);

foreach ($lines as $line_num => $dataset) {
    //output
}
share|improve this question

2 Answers 2

up vote 1 down vote accepted

Use a custom sort function:

EG:

uasort($lines, function($a , $b){
    $ex_a = explode('|', $a);
    $ex_b = explode('|', $b);

    return (strcmp($ex_a[1], $ex_b[1]) < 0 ? 1: -1); // change the < to > if they are in reverse...

}

print_r($lines);
share|improve this answer
up vote 0 down vote

Here is a method without a custom sort function.

This can be refactored if the number of columns is unknown.

<?php

$raw_records = 'Value_1|2|Value_3|Value_4|Value_5
Value_1|5|Value_3|Value_4|Value_5
Value_1|3|Value_3|Value_4|Value_5';

$records = array();

$lines = explode("\n", $raw_records);

foreach ($lines as $line_num => $dataset) {

    $dataset = explode('|', $dataset);

    $records[$dataset[1]][] = $dataset[0];
    $records[$dataset[1]][] = $dataset[2];
    $records[$dataset[1]][] = $dataset[3];
    $records[$dataset[1]][] = $dataset[4];
}

ksort($records, SORT_NUMERIC);

echo '<pre>'; var_dump($records); echo '</pre>';
?>
share|improve this answer
    
You are overcomplicating your answer, a custom sort function takes advantage of the "iteration" the sort methods do, so you only have to compare the specific condition. –  Frederic Yesid Peña Sánchez Feb 6 at 19:46

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