How to add entries to an empty dictionary using a formatted key, and update the value using the same key?

Question

I need to make an appointment calendar application in Python.

I have this empty dictionary called appointments and I’m trying to add appointments. It’s working but for some reason it’s not accumulating the appointments:

appointments = {}
while (True):
(... I had a choice variable here that would ask the user to either make an appointment, cancel, or view list of appointments. but for right now, i am only focusing on making appointments.)

    elif choice == 1: #Making an appointment
        apptDate = input('Enter date (mm/dd/yy)n')
        apptTime = input('Enter time (hh:mm)n')
        apptDesc = input('Enter a brief description of the appointmentn')

        #Checking to see if key in dictionary
        if apptDate not in appointments:
           newAppt = apptTime + 't' + apptDesc
           appointments[apptDate] = newAppt
        else:
           appointments[apptDate] = newAppt

I have to place apptTime + 't' + apptDesc in the appointments dictionary using apptDate as the key. I thought I was doing this right.
Check to see if apptDate is already in the appointments dictionary because it affects the way that it supposedly adds the new appointment.

Asked By: yummyyenni

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Source

Answer 1

appointments = []

is a list

appointments = {}

is a dictionary

to check if a key is in a dictionary use

if key in dictionary:

(where key would be apptDate)

Answered By: Joran Beasley

Answer 2

For your purposes use a defaultdict from collections module. This allows you to initialise your dictionary to give a key a certain value if the key is not already in there. In your case you may want to consider each date having a list of appointments, so if there are no appointments, the default dict is initialised with an empty list:

from collections import defaultdict
def default():
    return []

appointments = defaultdict(default)

Then, whenever you want to add an appointment to a key, you just do

appointments['date'].append("Info")

This is pretty clean, and avoids the checking statements.

If you insist doing it your way, your last paragraph can be:

if apptDate not in appointments:
    newAppt = apptTime + 't' + apptDesc
    appointments[apptDate] = [newAppt]
else:
    newAppt = apptTime + 't' + apptDesc
    appointments[apptDate].append(newAppt)

Answered By: user3684792

How to add entries to an empty dictionary using a formatted key, and update the value using the same key?

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