Group rows of a 2d array by a column value and push whole rows into grouped subarrays [duplicate]

Question

i've got the following array:

$comments   = array();
$comments[] = array('member_id' => '17',
                    'time'      => '2011-05-10 11:10:00',
                    'name'      => 'John Smith',
                    'comment'   => 'Test Comment 1');
$comments[] = array('member_id' => '25',
                    'time'      => '2011-05-10 11:26:00',
                    'name'      => 'David Jones',
                    'comment'   => 'Test Comment 2');
$comments[] = array('member_id' => '17',
                    'time'      => '2011-05-10 13:15:00',
                    'name'      => 'John Smith',
                    'comment'   => 'Test Comment 3');

How would i go about grouping it by member_id? So I'll be able to display the comments on the page with the following formatting:

John Smith(2 comments)

2011-05-10 11:10:00 | Test Comment 1
2011-05-10 13:15:00 | Test Comment 3

David Jones(1 comment)

2011-05-10 11:26:00 | Test Comment 2

Emil Vikström · Accepted Answer · 2011-05-10 06:22:22Z

4

One solution is to sort them by the name field (check out usort for that), but even easier might be to just populate a new array in this way:

$grouped = array();
foreach($comments as $c) {
  if(!isset($grouped[$c['name']]) {
    $grouped[$c['name']] = array();
  }

  $grouped[$c['name']][] = $c;
}

//Now it's just a matter of a double foreach to print them out:
foreach($grouped as $name => $group) {
  //print header here
  echo $name, "<br>\n";

  foreach($group as $c) {
    //print each comment here
  }
}

answered May 10, 2011 at 6:22

Emil Vikström

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2 Comments

Emil Vikström Over a year ago

Also note that you can get the comments sorted by the author's name using ksort after the first foreach loop.

mickmackusa Over a year ago

When using square brace pushing syntax, it is not necessary to instantiate an empty array before pushing children into it.

ANisus · Accepted Answer · 2011-05-10 06:24:05Z

2

I would suggest using a second grouping array

$groups[] = array();
foreach( $comment as $k=>$v ) {
    $groups[$v['member_id']][] = $k
}

And then to print it

foreach( $group as $m_id=>$arr ) {
    echo "Group $m_id<br/>\n";
    foreach( $arr as $k ) {
        echo $comment[$k]."<br/>\n";
    }
}

answered May 10, 2011 at 6:24

ANisus

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Comments

kapa · Accepted Answer · 2011-05-10 06:53:48Z

1

You should try with taking multi-dimensional array.

 $comment_groups[] = array();
    $m_id = '';

    foreach( $comment_groups as $key=>$val ) {
         if($key == 'member_id'){
             $m_id = $val;
            }
           $comment_groups[$m_id]][] = $val;
   }

Then you can print as you want to display.

edited May 10, 2011 at 6:53

kapa

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answered May 10, 2011 at 6:29

Chandresh M

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