change a value of nested dictionary in Python

Question

I am having some trouble updating a value of a nested dictionary. When I try to amend a value in a specific dictionary key, it changes all corresponding keys.

For example,

timetable_slots
 {'Monday': {1: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 2: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 3: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 'Lunch Time': 'Lunch Time', 5: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 6: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 7: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 8: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}}, 
 'Tuesday': {1: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 2: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 3: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 'Lunch Time': 'Lunch Time', 5: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 6: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 7: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 8: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}},
 'Wednesday': {1: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 2: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 3: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 'Lunch Time': 'Lunch Time', 5: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 6: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 7: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 8: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}}, 
 'Thursday': {1: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 2: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 3: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 'Lunch Time': 'Lunch Time', 5: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 6: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 7: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 8: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}}, 
 'Friday': {1: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 2: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 3: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 'Lunch Time': 'Lunch Time', 5: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 6: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 7: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 8: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': None, 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}}}

The above is the initial dictionary.

days_list = ['Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday']
period_list = range(1, 8)
group_list = ['Art10_1', 'Art10_2', ...]
possible_classroom_list = ['C10', 'C12', 'C20'] # This is possible classrooms to 'Art10_1'
idx = 0
count = 0

for group in group_list:
  while assign_finished == False:
    for day in days_list:
       for period in period_list:
          if period != 'Lunch Time':
              for key, value in timetable_slots[day][period].items(): # key = classroom, value = assigned classrooms which are set to None initially
                                if key == possible_classrooms[possible_classroom_idx]:
                                    if value == None:
                                        timetable_slots[day][period][key] = group
                                        possible_classroom_idx = 0
                                        count += 1
                                        if count == 3:
                                            assign_finished = True
                                        break

                                    else:
                                        possible_classroom_idx += 1
                                        if possible_classroom_idx == len(possible_classrooms):
                                            possible_classroom_idx = 0

This results in updating all the values with key C10 when I (think) specifically assigned to for example, timetable_slots['Monday'][1]['C10'] ??

timetable_slots
{'Monday': {1: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 2: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 3: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 'Lunch Time': 'Lunch Time', 5: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 6: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 7: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 8: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}}, 
'Tuesday': {1: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 2: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 3: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 'Lunch Time': 'Lunch Time', 5: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 6: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 7: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 8: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}}, 
'Wednesday': {1: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 2: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 3: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 'Lunch Time': 'Lunch Time', 5: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 6: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 7: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 8: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}}, 
'Thursday': {1: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 2: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 3: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 'Lunch Time': 'Lunch Time', 5: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 6: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 7: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 8: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}}, 
'Friday': {1: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 2: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 3: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 'Lunch Time': 'Lunch Time', 5: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 6: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 7: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}, 8: {'C1': None, 'C2': None, 'C3': None, 'C4': None, 'C5': None, 'C6': None, 'C7': None, 'C8': None, 'C9': None, 'C10': 'Art10_1', 'C11': None, 'C12': None, 'C13': None, 'C14': None, 'C15': None, 'C16': None, 'C17': None, 'C18': None, 'C19': None, 'C20': None, 'C21': None, 'C22': None, 'C23': None}}}

What am I missing and doing wrong?

Your dictionary contains the same reference to the same inner dictionary as value. Try `print(id(timetable_slots["Monday"][1]))` and `print(id(timetable_slots["Friday"][1]))` -. you'll see that the IDs printed are identical. ==> you reference the same inner dictionary for all your ``print(id(timetable_slots[ whatever here ][1]))``. Lists and Dicts are both reference types, read the dupe as to how to avoid that mishap. — Patrick Artner, Mar 25 '20 at 14:02
Okay, I understood why it's caused. But then how would you go on to fix it? How can I make each element in days_list with different references? — Lee Daniel, Mar 25 '20 at 14:30
`ts = {}; for day in ['M','T','W','Thu','F']: ts[day] = {}; for k in range(1,9): ts[day][k] = {}; for n in range(1,24): ts[day][k][f"C{n}"] = None` (all indentent into each other) - essentially: do not prepare one filled dict and insert it as multiple values... — Patrick Artner, Mar 25 '20 at 15:02

change a value of nested dictionary in Python

0 Answers0