How to count one array to fill another array?

Question

I have one array stores grade names, with grade value as key and grade name as value:

$labels=array(1=>'Insufficient',2=>'Sufficient',3=>'Satisfactory',4=>'Good',5=>'Excellent' );

Then, there's another array stores all record of people who gained a grade, with user_id as key and grade value as value:

$grades = array( 123 = > 1, 456 => 5 , 789 = > 3);

Now I want to count the record under each grade-- grade-1 => 5 users, grade-2=>6 users, in the form like this:

array(1=>5, 2=>6, 3=>2, 4=>2, 5=>1);

I tried this and got errors of Undefined offset:

$result = array();

for($i=1;$i<=5;++$i)
{
    foreach($grades as $user_id=>$user_grade)
    {
        $result[$i] = ( $user_grade == $i ) ? $result[$i]+1 : $result[$i];
    }
}

How to get an result array of counting how many user under each grade?

Undefined offset: 1 in C:\xampp\htdocs\.... on line 479 , totally 5 error messages from Undefined offset: 1 to Undefined offset: 5 — Jenny
– Jenny, Commented Aug 21, 2012 at 8:51
emm, in your given data set, your code works just fine for me. i suppose your $grades array has many more grades than just shown here? can you post the entire $grades array? — Software Guy
– Software Guy, Commented Aug 21, 2012 at 9:00

VolkerK · Accepted Answer · 2012-08-21 09:32:01Z

3

Sounds like array_count_values() would do the trick.

e.g.

<?php
$grades = array ( // this array contains no value "1"
   68 => 4, 138 => 4, 189 => 2, 255 => 4,
  297 => 3, 366 => 2, 425 => 4, 465 => 3,
  489 => 5, 580 => 4, 646 => 4, 704 => 5,
  784 => 2, 811 => 4, 897 => 4, 974 => 5,
  1006 => 2, 1093 => 2, 1189 => 2, 1222 => 4
);

$cnt = array_count_values($grades);
$cnt += array(1=>0,0,0,0,0);
ksort($cnt);

print_r($cnt);

prints

Array
(
    [1] => 0
    [2] => 6
    [3] => 2
    [4] => 9
    [5] => 3
)

edited Aug 21, 2012 at 9:32

answered Aug 21, 2012 at 8:55

VolkerK

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2 Comments

Jenny Over a year ago

Thanks! but, with array_count_values, the grades without any users will be left out. I need it to be filled with zero if no user has gained this grade.

Jenny Over a year ago

solved! I add $temp[$k] = isset($count[$k])?$count[$k]:0; to fill the empty grades.

Rahul Dev Sharma · Accepted Answer · 2012-08-21 09:50:06Z

0

Try It :

// $labels = array("Grade Value" => "Grade Name")
$labels=array(1=>'Insufficient',2=>'Sufficient',3=>'Satisfactory',4=>'Good',5=>'Excellent' );

// $grades = array("User Id" => "Grade Value")
$grades = array( 123 => 1, 456 => 5 , 789 => 3);

//OutPUT :  array( "Gread Value " => "No Of Users ")

foreach($labels as $key => $value)
{
    $userCount = 0;
    foreach($grades as $key1=> $value1)
    {
        if($key == $value1)
        {
            $userCount++;
        }
    }

    $result[$key] = $userCount;
}

print_r($result);

answered Aug 21, 2012 at 9:50

Rahul Dev Sharma

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