selecting items from an array

I have a text file which is read into an array $data using fgets(). The data is then split into further arrays by tab delimiter. I would like to find a way of extracting and printing items from $data using a form. The form fields (e.g. grade, subject) are populated from the arrays. When the user selects a subject and grade, then clicks the button, I would like to select and print only the data, in this case from the array $expect, where the grade is $grade_selected and the subject is $subject_selected. I would appreciate help with how to select and print the relevant data. Many thanks, Peter Gumbrell peter@orillia.net