Sort and display array values according to a value?

Question

Given the following PHP array:

Array
(
    [0] => Array
        (
            [name] => Restaurant 123
            [city] => Arlington
            [zip] => 22201
        )

    [1] => Array
        (
            [name] => Bar Foo
            [city] => Ballston
            [zip] => 22201
         )
     [2] => Array
        (
            [name] => Restaurant XYZ
            [city] => Ballston
            [zip] => 22201
         )

    [3] => Array
        (
            [name] => Restaurant 321
            [city] => Washington DC
            [zip] => 22201
         )

)

How can I produce a list sorted according to city (alphabetically), so that it would output something like:

Arlington

Restaurant 123

Ballston

Bar Foo

Restaurant XYZ

Washington DC

Restaurant 321

E.G., sorted first by city name alphabetically, and then by venue name, also alphabetically. Also note that it's not given that the restaurant name, nor the cities are alphabetically sorted in the array given.

Oswald · Accepted Answer · 2011-01-09 20:59:54Z

2

Write a callback function that you can pass to usort, for example

function compare_venues($a, $b)
{
  return strcmp($a['name'], $b['name']);
}

answered Jan 9, 2011 at 20:59

Oswald

31.8k3 gold badges45 silver badges72 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

João Silva · Accepted Answer · 2011-01-09 21:00:04Z

2

You can use usort, which enables you to sort an array based on a user-defined comparison function.

answered Jan 9, 2011 at 21:00

João Silva

91.8k29 gold badges156 silver badges158 bronze badges

Comments

Michele · Accepted Answer · 2011-01-09 21:00:29Z

2

Try usort ( http://php.net/manual/en/function.usort.php ) where you can define a custom sort schema like

function cmp($a, $b)
{
    if ($a == $b) {
        return 0;
    }
    return ($a < $b) ? -1 : 1;
}

answered Jan 9, 2011 at 21:00

Michele

6,1392 gold badges43 silver badges46 bronze badges

Comments

jon_darkstar · Accepted Answer · 2011-01-09 21:39:38Z

1

Looks like theres two parts to what you want - sorting and displaying.

To sort, you want to use usort with small function defining the comparison

$sortFunc = function($a,$b) {return $a['city'] != $b['city'] 
                                 ? $a['city'] > $b['city']
                                 : $a['name'] > $b['name'];};

        // = function($a,$b) {return $a['city'] > $b['city'] || ($a['city'] == $b['city'] && $a['name'] > $b['name']);};
        // = function($a,$b) {return 100*strcmp($a['city'],$b['city']) + strcmp($a['name'],$b['name']);};
usort($arr, $sortFunc);

function displayNamesGroupedByCity($arr)
{
    $lastCity = '';
    foreach($arr as $v)
    {
        if ($v['city'] != $lastCity)
        {
             $lastCity = $v['city'];
             echo "<br /><strong>$lastCity</strong><br />";
        }
        else echo ', ';
        echo $v['name'];
    }
}

displayNamesGroupedByCity($arr);

For the hell of it im going to make things generic

function displayXgroupedByY($arr, $x, $y)
{
    $sortFunc = function($a,$b) use($x,$y) 
                               {return $a[$y] != $b[$y] 
                                 ? $a[$y] > $b[$y]
                                 : $a[$x] > $b[$y];};

    user($arr, $sortFunc);

    $lastCity = '';
    foreach($arr as $v)
    {
        if ($v['city'] != $lastCity)
        {
             $lastCity = $v['city'];
             echo "<br /><strong>$lastCity</strong><br />";
        }
        else echo ', ';
        echo $v['name'];
    }
    return $arr;
}

displayXGroupedByY($arr, 'name', 'city');

edited Jan 9, 2011 at 21:39

answered Jan 9, 2011 at 21:01

jon_darkstar

16.9k7 gold badges35 silver badges38 bronze badges

5 Comments

Slater Over a year ago

Hi Jon, I tried your sort function but a print_r($sorted) just gives me "1" instead of a sorted list? Apart from the missing apostrophes which I guess SO removed.

jon_darkstar Over a year ago

yes, i fixed it. usort sorts in place, the return value is boolean

Slater Over a year ago

OK cool, this ALMOST works, except the items seem to be in reverse order, eg. both the cities and the venues are backwards?

jon_darkstar Over a year ago

hah i just noticed that myself. you switched the comparisons to less thans i guess?

Slater Over a year ago

I just reversed the $a, $b in the $sortFunc = function() :)

Community · Accepted Answer · 2023-11-20 22:45:59Z

1

user defined sorting should do a work:

https://www.php.net/manual/en/function.uasort.php

edited Nov 20, 2023 at 22:45

CommunityBot

11 silver badge

answered Jan 9, 2011 at 21:04

bensiu

25.7k56 gold badges81 silver badges117 bronze badges

Collectives™ on Stack Overflow

Sort and display array values according to a value?

5 Answers 5

Comments

Comments

Comments

5 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

5 Answers 5

Comments

Comments

Comments

5 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related