How to find the mode of an array in PHP

Question

I have an array that has been sorted from low to high which has over 260k values in. I have found out the mean(average) and median of the array just need to find out the mode?

I cannot use any mathematical functions that PHP has, it has to be all done manually.

I would like it so there could be just one value that is the mode but then there can be multiple values that can be the mode. I also need to be able to record the number of times that the value is stored. For example the number 51 appears 6 times so I can print both values.

This is my code so far:

$amountRecords = 0;
$totalValue = 0;
$valueArray = array();

// reads in csv file
$handle = fopen('Task1-DataForMeanMedianMode.csv', 'r');
// to skip the header names/values
fgetcsv($handle);

// creates array containing variables of csv file in ascending order
while(($row = fgetcsv($handle, "\r")) != FALSE)
{

    // if amountRecords equals 0
    if($amountRecords == 0)
    {

        // adds value from csv to array
        $valueArray[] = $row[1];

    } // else amountRecords does not equal 0
    else 
    {

        // if the value in array location before is greater than the current value from the csv file
        if($valueArray[$amountRecords - 1] > $row[1])
        {

             // the current array location becomes the one in the location before
             $valueArray[] = $valueArray[$amountRecords - 1];
             // add the value from the csv to the location before
             $valueArray[$amountRecords - 1] = $row[1];

         } // if the value in the location before is not greater than the current value in the csv file
         else 
         {

             // adds value from csv to array
             $valueArray[] = $row[1];

         }

    }

    // calculates the total value of the values in csv file
    $totalValue = $totalValue + $row[1];
    // calculates the number of values in the csv file
    $amountRecords++;

}    

// calculate average value of payments
$averageValue = $totalValue / $amountRecords;
// limit integer to 2 decimal place
$average = number_format($averageValue,2,'.','');

// finds middle value
$middle = floor(($amountRecords / 2) - 1);

// calculates the median value
// if array size is even
if($amountRecords % 2 == 0)
{

    // calculates median
    $median = $valueArray[$middle];

} 
else // if array size is odd
{

    // calculate low and high values
    $low = $valueArray[$middle];
    $high = $valueArray[$middle + 1];
    // calculates median
    $median = (($low + $high) / 2);

}

// works out mode
// creates array count
$count = array();
// for each value in the valueArray
foreach( $valueArray as $value )
{

    if( isset( $count[$value] ))
    {

        $count[$value]++;

    }
    else
    {

        $count[$value] = 1;

    }

}

$mostCommon = "";
$iter = 0;

foreach( $count as $k => $v )
{

     if( $v > $iter )
     {

         $mostCommon = $k;
         $iter = $v;

     }

}

$modeArray = array( "mode" => $mostCommon , "count" => $iter );

Solution 1

The mode of a numerical set is the number that occurs the most often. You can do this with PHP using code similar to the following:

$values = array_count_values($valueArray); 
$mode = array_search(max($values), $values);

Solution 2

Simple!

$arr = array(4,6,7,1,4,7,4,7,1);
$freq = array();
for($i=0; $i<count($arr); $i++)
{
   if(isset($freq[$arr[$i]])==false)
   {
       $freq[$arr[$i]] = 1;
   }
   else
   {
       $freq[$arr[$i]]++;
   }
}
$maxs = array_keys($freq, max($freq));

for($i=0; $i<count($maxs); $i++)
{
   echo $maxs[$i] . ' ' . $freq[$maxs[$i]];
   echo '<br />';
}

Comments

[Admin]

Like I said in my post it has to be done manually without using any mathematical functions PHP has. This includes count and max and min etc.

[White Elephant]

Have a go at working out the mode and then we can help you out with it. Based on the code above, it looks like you haven't even attempted it.

[Admin]

@WhiteElephant I have something but it only returns one value not multiple if there multiple. I have edited my original post with the added mode code that I have done.

[kayla]

This solution is good, but if there are more than one mode numbers, its only pick the first one of the order in the array. I am trying to get all numbers that occurs the most often, for example {2,2,3,3,1} -> I need to get 2 and 3. Can you have any other solution? Sorry for my poor English

[8ctopus]

solution with multiple modes: $values = array_count_values($cells); asort($values); $modes = array_keys($values, max($values));