Dictionary as a MAP type

course_professors = {‘calculus’: ‘Prof. Kotter’,

‘diff eq’: ‘Prof. Feeny’, ‘linear algebra’: ‘Prof. Kotter’, ‘real analysis’: ‘Prof. Crabtree’}

student_courses = {‘vinnie’: {‘calculus’, ‘diff eq’},

‘arnold’: {‘calculus’, ‘linear algebra’}, ‘juan luis’: {‘real analysis’}}

Which student has which professor?

student_professors = {}

for student in student_courses:
    for course in student_courses[student]:
        if student not in student_professors:
            # use set to remove duplicates
            student_professors[student] = set()
        student_professors[student].add(course_professors[course])

student_professors

Output:

{'vinnie': {'Prof. Feeny', 'Prof. Kotter'},
 'arnold': {'Prof. Kotter'},
 'juan luis': {'Prof. Crabtree'}}

Which professor has which student?

professor_students = dict()

for course, professor in course_professors.items():
    for student, courses in student_courses.items():
        if course in courses:
            if professor not in professor_students:
                # use set to remove duplicates
                professor_students[professor] = set()
            professor_students[professor].add(student)

professor_students

Output:

{'Prof. Kotter': {'arnold', 'vinnie'},
 'Prof. Feeny': {'vinnie'},
 'Prof. Crabtree': {'juan luis'}}