TypeError: string indices must be integers, not str // working with dict

Question

I am trying to define a procedure, involved(courses, person), that takes as input a courses structure and a person and returns a Dictionary that describes all t

Answer 1

I see that you are looking for an implementation of the problem more than solving that error. Here you have a possible solution:

from itertools import chain

def involved(courses, person):
    courses_info = chain.from_iterable(x.values() for x in courses.values())
    return filter(lambda x: x['teacher'] == person, courses_info)

print involved(courses, 'Dave')

The first thing I do is getting the list of the courses and then filter by teacher's name.