Nested dictionary for loop with def (INDENTENTION PROBLEM)

Question

I am learning Python with the 2°Ed. Automate the boring stuff with python, and I came across with a indentention problem.

Can someone explain what I am doing wrong?

I am trying to add a indentention after the for loop to insert the num_brought value, but it keeps getting an error: TypeError: unsupported operand type(s) for +: 'int' and 'str'.

Book code:

allGuests = {'Alice': {'apples': 5, 'pretzels': 12},
             'Bob': {'ham sandwiches': 3, 'apples': 2},
             'Carol': {'cups': 3, 'apple pies': 1}}

def totalBrought(guests, item):
    numBrought = 0
    for k, v in guests.items():
        numBrought = numBrought + v.get(item, 0)
    return numBrought
    
print('Number of things being brought:')
print(' - Apples         ' + str(totalBrought(allGuests, 'apples')))
print(' - Cups           ' + str(totalBrought(allGuests, 'cups')))
print(' - Cakes          ' + str(totalBrought(allGuests, 'cakes')))
print(' - Ham Sandwiches ' + str(totalBrought(allGuests, 'ham sandwiches')))
print(' - Apple Pies     ' + str(totalBrought(allGuests, 'apple pies')))

My code:

all_guests = {
    'Alice': {'apple': 1, 'ham': 2},
    'Joe': {'potato': 7, 'beer': 7},
    'Carl': {'apple': 3, 'beer': 'none'}}

def total_brought(guest, item):
    num_brought = 0
    for k, v in guest.items():
        num_brought = num_brought + v.get(item, 0)
    return num_brought

print('Total brought: ')
print('Apples: ' + str(total_brought(all_guests, 'apple')))
print('Beer: ' + str(total_brought(all_guests, 'beer')))
print('Ham: ' + str(total_brought(all_guests, 'ham')))
print('Potato: ' + str(total_brought(all_guests, 'potato')))

I kind of solved by changing the beer from none to a int value. I think that the fact that they are different kind of data types, the code can't communicate and add to the num_brought variable. Thanks, Michael to highlight that!! — THIAGO SAMPAIO, Mar 12 '23 at 02:00
I posted an answer explaining that in more depth below. Did that change work for you? — Michael M., Mar 12 '23 at 02:00
An alternative way would also is to check for the `'none'` string and handle it accordingly, however changing your data is probably simpler if you can. — Michael M., Mar 12 '23 at 02:03
Welcome to Stack Overflow. " and I came across with a indentention problem." I can't understand why you think so. The error message says "TypeError: unsupported operand type(s) for +: 'int' and 'str'.". Do you see anything about indentation in there? — Karl Knechtel, Mar 12 '23 at 04:50
In your own words, what do you think will happen when the code looks up the amount of beer that Carl brought? Why should it be possible, to add that result to `7`? What do you think the result should be, and why? — Karl Knechtel, Mar 12 '23 at 04:51

score 0 · Accepted Answer · answered Mar 12 '23 at 01:59

The issue is your data, not your indentation. On this line

num_brought = num_brought + v.get(item, 0)

you add num_brought (a number) to a value of one of the dictionaries in allGuests. In the book, all of those values are numbers too, but in your data, one of them is the string 'none' (allGuests['Carl']['beer']).

The solution is to just change that data to 0, as the number zero means having nothing, or "none":

all_guests = {
    'Alice': {'apple': 1, 'ham': 2},
    'Joe': {'potato': 7, 'beer': 7},
    'Carl': {'apple': 3, 'beer': 0}}

def total_brought(guest, item):
    num_brought = 0
    for k, v in guest.items():
        num_brought = num_brought + v.get(item, 0)
    return num_brought

print('Total brought: ')
print('Apples: ' + str(total_brought(all_guests, 'apple')))
print('Beer: ' + str(total_brought(all_guests, 'beer')))
print('Ham: ' + str(total_brought(all_guests, 'ham')))
print('Potato: ' + str(total_brought(all_guests, 'potato')))

Alternatively, you can check for the value 'none' and change it to zero in your function:

all_guests = {
    'Alice': {'apple': 1, 'ham': 2},
    'Joe': {'potato': 7, 'beer': 7},
    'Carl': {'apple': 3, 'beer': 'none'}}

def total_brought(guest, item):
    num_brought = 0
    for k, v in guest.items():
        val = v.get(item, 0)
        if val == 'none':
            val = 0

        num_brought = num_brought + val
    return num_brought

print('Total brought: ')
print('Apples: ' + str(total_brought(all_guests, 'apple')))
print('Beer: ' + str(total_brought(all_guests, 'beer')))
print('Ham: ' + str(total_brought(all_guests, 'ham')))
print('Potato: ' + str(total_brought(all_guests, 'potato')))

Thanks, man. I am new to coding and Stack. Going to check right away. — THIAGO SAMPAIO, Mar 12 '23 at 02:05

Nested dictionary for loop with def (INDENTENTION PROBLEM)

1 Answers1