Finding students who appear on a list I'm new in Python and consequently I am searching for a specific solution for code development. I already asked some pythonic question today and want to present my whole problem.  I have found some solution, but I really have interest to develop easier and clearer code in Python, so all improvements are welcome. 

For example, in some school, the students are ordered to some of 3 different classes. Now I have some set of graduated students and want to know, how many graduated students are in some class.

I create next code:

physic = ['id_1', 'id_2', 'id_4']
chemistry = ['id_5', 'id_7']
math = ['id_3', 'id_8', 'id_9']

graduatedPhysic = []
graduatedChemistry = []
graduatedMath = []

classes = [physic, chemistry, math]
graduated = [graduatedPhysic, graduatedChemistry, graduatedMath]


Every class has the different number of students (given by students IDs) and gratuated Classes are at the first empty. I combine it also to list of lists.

Then I use my code:

graduatedlist = ['id_2', 'id_5', 'id_7']

for stud in graduatedlist:
    for pos1 in range(len(graduated)):
        for pos2 in range(len(classes[pos1])):
            if stud.find(classes[pos1][pos2]) != -1:
                graduated[pos1].append((stud))


This code works, but does not look great... I would be very grateful for comments! For example, I tried to implement the idea with itertools.product():

for item_1, item_2 in itertools.product(range(len(graduated)), range(len(classes[item_1])):


I have a problem with a declaration of item_1.

I have also a feeling that the lists isn't the best solution for implementation, but for DataFrame I need the column of similar length and every class can have the different number of the students.

For the special interest are two points:


How I really can improve my for-loop?
What I can use instead of list declaration?
I would strongly recommend creating a class.

class Student:
    def __init__(self, id, graduated):
        self.id = id
        self.graduated = graduated


Then your problem is easier.

graduatedchemistry = [student for student in chemistry if student.graduated]


To cleanly get graduates from all classes then you can make a function

def getgraduates(students):
    return [student for student in students if student.graduated]

graduatedchemistry = getgraduates(chemistry)
graduatedmath = getgraduates(math)