I am trying to sort a flat file (.txt) in descending order.
Here's the list inside file.txt (name, age, ID No.) :
Jason, 24, 18299
Bryan, 19, 12999
James, 32, 72990
My goal is to arrange the list in descending natural order based on the second column. I tried making a natrsort function to reverse the arrangement.
Here's what i came up with:
<?php
$rows = array();
$result = '';
$data = file('file.txt');
function natrsort(&$array) //the function i made to arrange them in descending order
{
natsort($array);
$array = array_reverse($array);
}
foreach($data as $key => $val) {
$rowarray = explode(",", $val);
$rows[] = $rowarray[1];
}
natrsort($rows);
//print_r($rows); When I use this, everything seems to work.
foreach($rows as $key => $val) {
$result .= trim($data[$key]) . "<br/>";
}
echo $result; //display the new sorted list
The output keeps displaying the same list. No Sorting happened. Maybe I am missing something?
When you use $data[$key], $key is equals to 0,1 and 2, because array_reverse() re-index the array. So, your printed array is in the same order than your data in the file.
You could use natsort(), then, reverse the array of keys only:
natsort($rows);
$indexes = array_reverse(array_keys($rows));
foreach ($indexes as $key) {
$result .= trim($data[$key]) . '<br>';
}
Prints:
James, 32, 72990<br>Jason, 24, 18299<br>Bryan, 19, 12999<br>
Another way is to sort using a custom sort function like usort():
$result = '';
$data = file('file.txt');
usort($data, function($a, $b) {
[, $ageA] = explode(',', $a);
[, $ageB] = explode(',', $b);
return intval($ageB) <=> intval($ageA);
});
foreach ($data as $val) {
$result .= trim($val) . '<br>';
}
echo $result;
Output:
James, 32, 72990<br>Jason, 24, 18299<br>Bryan, 19, 12999<br>
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