Stable sort an array of pipe-delimited strings only by the leading value

Question

I have an array that contains entries that themselves contain two types of entries.

For simplicity sake, let's say that the entries are like this:

a|1
b|4
a|2
c|5
b|3

etc.

In fact they represent categories and subcategories in my database.

I will use explode to break these entries into letters and digits.

The question is: I want to group them by category.

What's the easiest way to create a multilevel array, which could be sorted by letters:

a|1
a|2
b|4
b|3
c|5

?

This question is not very clear because the input and output "array" data is presented as pipe-delimited lines of a multiline string. — mickmackusa
– mickmackusa ♦, Commented Jan 15 at 23:11

Kokos · Accepted Answer · 2011-12-13 09:58:26Z

2

How about something like this?

$input  = array('a|1','b|4','a|2','c|5','b|3');
$output = array();

foreach($input as $i){

    list($key,$val) = explode("|",$i);
    $output[$key][] = $val;

}

Output:

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

[b] => Array
    (
        [0] => 4
        [1] => 3
    )

[c] => Array
    (
        [0] => 5
    )

)

answered Dec 13, 2011 at 9:58

Kokos

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1 Comment

Uno Mein Ame Over a year ago

this looks great. is there a way to access the values for keys, too? I mean - how would i know to use 'a', 'b', and 'c' unless I know these values?

njmu83 · Accepted Answer · 2011-12-13 09:57:12Z

0

<?php

$your_array = array();

$your_array[a] = array('1','2','3');
$your_array[b] = array('4','5','6');

print_r($your_array);

?>

answered Dec 13, 2011 at 9:57

njmu83

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1 Comment

njmu83 Over a year ago

sorry, to response to the question print_r(arsort(your_array));

MeLight · Accepted Answer · 2011-12-13 09:58:45Z

0

I take it that your entries are strings (relying on the fact that you want to use explode() on them).

If so you can simply sort the array by using sort($array), and then iterate on that array and explode the values and put them in another array, which will be sorted by the previous array's order.

answered Dec 13, 2011 at 9:58

MeLight

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