Question

Code Written In Python

# Following Are The 3 Lists
sections = ['A', 'B', 'A', 'A', 'B']
students = ['Jack', 'Jim', 'Jack', 'Leena', 'Jim']
subjects = ['Maths', 'Biology', 'Chemistry', 'English', 'Physics']

# The Output Should Be A Dictionary
classDict = {'A':{'Jack' :{1:'Maths', 2:'Chemistry'}, 'Leena':{1:'English'}}, 'B':{'Jim':{1:'Biology', 2:'Physics'}}}

I can merge any of the two list into one dictionary, taking only first two lists in account

classDict = {}   
for stu in students:  
    if not stu in classDict:     
        classDict[stu] = []    
    classDict[stu].append(stu)  

But unable to extend it to n(n=3, in my case) list.

Answer 1

defualtdict and zip are your friends for this one:

I believe the following would work.

class_dict= defaultdict(lambda: defaultdict(lambda: defaultdict(str)))
for (section, stu, sub) in zip(sections, students, subjects):
    l = len(class_dict[section][stu])
    class_dict[section][stu][l+1] = sub

you could even do this in one line if you really wanted to.