How to find the largest array from a multi dimensional array [duplicate]

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Closed 13 years ago.

Possible Duplicate:
Get the maximum value from an element in a multidimensional array?
find max() of specific multidimensional array value in php

Iam trying to find out the largest array from multi dimensional array.

Array
(
 [0] => Array
 (
 [comment] => ayya
 [commented_on] => 17/03/12
 [ckey] => 210029c5d80d8259d1599c9a
 [username] => pappa
 [up] => 2
 [down] => 0
 [vote] => 2
 )
 [1] => Array
 (
 [comment] => sdfsd
 [commented_on] => 17/03/12
 [ckey] => 08f6a34f96bdeef2903ddaf4
 [username] => jesse
 [up] => 2
 [down] => 0
 [vote] => 2
 )
 [2] => Array
 (
 [comment] => 159
 [commented_on] => 17/03/12
 [ckey] => 4da385124793336339268782
 [username] => jesse
 [up] => 2
 [down] => 0
 [vote] => 2
 )
 [3] => Array
 (
 [comment] => s
 [commented_on] => 17/03/12
 [ckey] => 299c77c52ee087e468e23e82
 [username] => jesse
 [up] => 2
 [down] => 0
 [vote] => 2
 )
 [4] => Array
 (
 [comment] => jh
 [commented_on] => 17/03/12
 [ckey] => 523c18820d8b8db827a240ad
 [username] => jesse
 [up] => 2
 [down] => 0
 [vote] => 2
 )
 [5] => Array
 (
 [comment] => jh
 [commented_on] => 17/03/12
 [ckey] => 9f824c11b0ecafcc38c09f4c
 [username] => jesse
 [up] => 1
 [down] => 1
 [vote] => 0
 )
 [6] => Array
 (
 [comment] => jh
 [commented_on] => 17/03/12
 [ckey] => c97e7ad4d205220c4b8b0332
 [username] => jesse
 [up] => 1
 [down] => 0
 [vote] => 1
 )
)

I would like to get the array having highest votes. Highest means the array having highest vote

I have used the following code, but it is not working.

$large=array();
 foreach($final2 as $f1){
 foreach($final2 as $f2){
 if($f1['vote']>$f2['vote'])
 $large=$f1;
 }
 }

• sunil kumar: $large=array(); foreach($final2 as $f1){ foreach($final2 as $f2){ if($f1['vote']>$f2['vote']) $large=$f1; } } op($large)
• Felix Kling: Please edit your question and add your code. It's unreadable in comments.
• John Carter: @sunilkumar you seem to be on the right track, I'm assuming the second foreach is a copy & paste error since it's not needed.
• DarkMukke: just wrote a oneliner for it $maxs = $multi[array_keys(array_map(function( $row ){ return count($row['vote']); }, $multi ), max(array_map(function( $row ){ return count($row['vote']); }, $multi )))[0]];

Answer 1

AFAIK array size is counted from the number of elements it has.

So may be this will help

$largeArraySize = 0;
foreach($arraylist as $array) {
 if(count($array) > $largeArraySize) {
 $largeArray = $array;
 }
}
// Hence $largeArray has the largest
print_r($largeArray);

Unless a large array come this code will take the first occurrence as the largest.

• user3413723: you need to change $largeArraySize to equal count($array); each time a new larger array is found.
• DarkMukke: or a 1 liner : $max = max( array_map(function( $row ){ return count($row); }, $multi ) )

Answer 2

Since the array is only nested one level deep and all the sub-arrays have the same structure, just loop through the outer array and track the maximum value seen so far. Nice and simple.

Answer 3

Without additional information such as whether the array is already sorted on number of votes, the only option you have left is a O(n) linear search.

$max = 0;
$max_index = 0;
if( count($outer_array) > 0 )
{
 // There are elements in the outer array
 for($i = 0; $i < count($outer_array); $i++ )
 {
 if( isset($outer_array[$i]["vote"]) )
 {
 if( $outer_array[$i]["vote"] > $max )
 {
 $max_index = $i;
 }
 }
 else
 {
 // Error condition, malformed array
 // Do something here, maybe throw exception?
 } 
 }
}
else
{
 // Error condition - outer array is empty, could also throw exception here...
 $max = -1; // Assume votes cannot be negative
 $max_index = -1;
}
if( $max_index != -1 )
{
 // Success
 // Do something...
}

Answer 4

This should give you an idea to get the highest number of votes in the inner arrays:

$array = array(
 array('votes' => 2),
 array('votes' => 3),
 array('votes' => 0),
 array('votes' => 1)
);
$votes = 0;
$key = 0;
for($i = 0; $i < count($array); $i++){
 if($array[$i]['votes'] > $votes){
 $key = $i;
 $votes = $array[$i]['votes'];
 }
}

Answer 5

Change your code to:

$large=array('vote' => -1);
foreach($final2 as $f1){
 if ($f1['vote'] > $large['vote']) {
 $large=$f1;
 }
}

Answer 6

$array = array(.....)
$max_votes = 0;
foreach ($array as $data) {
 $vote = $data['vote'];
 if ($vote > $max_vote) {
 $max_vote = $vote;
 } 
}
$max = array();
foreach ($array as $key => $data) {
 if ($data['vote'] == $max_vote) {
 $max[] = $key;
 }
}

$max will now hold all of the arrays with the highest number of votes being the value of $max_votes.