filtering dictionary items

Question

I have a question regarding inverse filtering in dictionary. I have a dictionary as:

dico = {
   Pierre:{
         'Math':16,
         'Chimie':09,
         'Dessin':18,
         'Electronic':20,
         'Info':14,
         }
    Jean:{
         'Physics':10,
         'Chimie':20,
         'Dessin':13,
         'Electronic':16,
         'Info':17,
         }
    Giovani:{
         'Math':16,
         'Physics':14,
         'Chimie':13,
         'Dessin':14,
         'Electronic':17,
         'Info':12,
         }

    ...
    }

What I want is to extract all the student which attempt each exam, and have output as set or list such as:

'Math': [pierre,Giovanie], 'Physics': [Jean, Giovanie]

exam_set = [{k:v for (k, v) in i.items()}
                for i in dico if i.get(v) != 0]

But is doesn't work and I don't know how to how to fix that.

Answer 1

i commented everything play with the code so you can get better at python

students = { # students
"Pierre":{
         'Math':16,
         'Chimie':90,
         'Dessin':18,
         'Electronic':20,
         'Info':14,
         },
"Jean":{
         'Physics':10,
         'Chimie':20,
         'Dessin':13,
         'Electronic':16,
         'Info':17,
         },
"Giovani":{
         'Math':16,
         'Physics':14,
         'Chimie':13,
         'Dessin':14,
         'Electronic':17,
         'Info':12,
         }
         
}
data = {} # create data dict

for student in students: # loop to every student
    for exam in students[student]: # loop in the student exams
        if exam in data: # check if exam list exist
            data[exam].append(student) # append to the exam list
        else: # else create an exam list
            data[exam] = [student] # create and add the student to the exam list

print(data) # let see the result