For example, you have an array of non-unique values that are student names, you know there are just 5 of them but a total of 15 elements exist in that array with some student names repeated in more than one elements.
To count the occurrences of all the unique values, in this case, 5 student names, in that array, simply use the PHP function array_count_values():
$counts = array_count_values($students);The resulted array looks like:
Array
(
['George'] => 3
['Clark'] => 2
['John'] => 4
['Annie'] => 1
['Betsy'] => 5
)