2023年3月12日 09:54:12go评论95阅读模式

英文:

Nested dictionary for loop with def (INDENTENTION PROBLEM)

问题

I am learning Python with the 2nd Edition of "Automate the Boring Stuff with Python," and I came across an indentation problem.

Can someone explain what I am doing wrong?

I am trying to add indentation after the for loop to insert the num_brought value, but I keep 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'))

(Note: I have corrected the indentation in your provided code to avoid the syntax error.)

英文:

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 = {&#39;Alice&#39;: {&#39;apples&#39;: 5, &#39;pretzels&#39;: 12},
             &#39;Bob&#39;: {&#39;ham sandwiches&#39;: 3, &#39;apples&#39;: 2},
             &#39;Carol&#39;: {&#39;cups&#39;: 3, &#39;apple pies&#39;: 1}}
def totalBrought(guests, item):
    numBrought = 0
    for k, v in guests.items():
        numBrought = numBrought + v.get(item, 0)
    return numBrought
	
print(&#39;Number of things being brought:&#39;)
print(&#39; - Apples         &#39; + str(totalBrought(allGuests, &#39;apples&#39;)))
print(&#39; - Cups           &#39; + str(totalBrought(allGuests, &#39;cups&#39;)))
print(&#39; - Cakes          &#39; + str(totalBrought(allGuests, &#39;cakes&#39;)))
print(&#39; - Ham Sandwiches &#39; + str(totalBrought(allGuests, &#39;ham sandwiches&#39;)))
print(&#39; - Apple Pies     &#39; + str(totalBrought(allGuests, &#39;apple pies&#39;)))

My code:

all_guests = {
    &#39;Alice&#39;: {&#39;apple&#39;: 1, &#39;ham&#39;: 2},
    &#39;Joe&#39;: {&#39;potato&#39;: 7, &#39;beer&#39;: 7},
    &#39;Carl&#39;: {&#39;apple&#39;: 3, &#39;beer&#39;: &#39;none&#39;}}
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(&#39;Total brought: &#39;)
print(&#39;Apples: &#39; + str(total_brought(all_guests, &#39;apple&#39;)))
print(&#39;Beer: &#39; + str(total_brought(all_guests, &#39;beer&#39;)))
print(&#39;Ham: &#39; + str(total_brought(all_guests, &#39;ham&#39;)))
print(&#39;Potato: &#39; + str(total_brought(all_guests, &#39;potato&#39;)))

答案1

得分: 0

问题出在你的数据上，而不是缩进上。在这一行

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

你将num_brought（一个数字）与allGuests中的一个字典的值相加。在书中，所有这些值也都是数字，但在你的数据中，其中一个是字符串'none'（allGuests['Carl']['beer']）。

解决方法是将该数据更改为0，因为数字零表示什么都没有，或者"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'))

或者，你可以在函数中检查值是否为'none'，并将其更改为零：

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'))

英文:

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 = {
    &#39;Alice&#39;: {&#39;apple&#39;: 1, &#39;ham&#39;: 2},
    &#39;Joe&#39;: {&#39;potato&#39;: 7, &#39;beer&#39;: 7},
    &#39;Carl&#39;: {&#39;apple&#39;: 3, &#39;beer&#39;: 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(&#39;Total brought: &#39;)
print(&#39;Apples: &#39; + str(total_brought(all_guests, &#39;apple&#39;)))
print(&#39;Beer: &#39; + str(total_brought(all_guests, &#39;beer&#39;)))
print(&#39;Ham: &#39; + str(total_brought(all_guests, &#39;ham&#39;)))
print(&#39;Potato: &#39; + str(total_brought(all_guests, &#39;potato&#39;)))

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

all_guests = {
    &#39;Alice&#39;: {&#39;apple&#39;: 1, &#39;ham&#39;: 2},
    &#39;Joe&#39;: {&#39;potato&#39;: 7, &#39;beer&#39;: 7},
    &#39;Carl&#39;: {&#39;apple&#39;: 3, &#39;beer&#39;: &#39;none&#39;}}
def total_brought(guest, item):
    num_brought = 0
    for k, v in guest.items():
        val = v.get(item, 0)
        if val == &#39;none&#39;:
            val = 0
        num_brought = num_brought + val
    return num_brought
print(&#39;Total brought: &#39;)
print(&#39;Apples: &#39; + str(total_brought(all_guests, &#39;apple&#39;)))
print(&#39;Beer: &#39; + str(total_brought(all_guests, &#39;beer&#39;)))
print(&#39;Ham: &#39; + str(total_brought(all_guests, &#39;ham&#39;)))
print(&#39;Potato: &#39; + str(total_brought(all_guests, &#39;potato&#39;)))

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