嵌套字典循环与def（缩进问题）

huangapple
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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:

  1. allGuests = {'Alice': {'apples': 5, 'pretzels': 12},
  2.              'Bob': {'ham sandwiches': 3, 'apples': 2},
  3.              'Carol': {'cups': 3, 'apple pies': 1}}
  5. def totalBrought(guests, item):
  6.     numBrought = 0
  7.     for k, v in guests.items():
  8.         numBrought = numBrought + v.get(item, 0)
  9.     return numBrought
  11. print('Number of things being brought:')
  12. print(' - Apples         ' + str(totalBrought(allGuests, 'apples')))
  13. print(' - Cups           ' + str(totalBrought(allGuests, 'cups')))
  14. print(' - Cakes          ' + str(totalBrought(allGuests, 'cakes'))
  15. print(' - Ham Sandwiches ' + str(totalBrought(allGuests, 'ham sandwiches'))
  16. print(' - Apple Pies     ' + str(totalBrought(allGuests, 'apple pies'))

My code:

  1. all_guests = {
  2.     'Alice': {'apple': 1, 'ham': 2},
  3.     'Joe': {'potato': 7, 'beer': 7},
  4.     'Carl': {'apple': 3, 'beer': 'none'}}
  6. def total_brought(guest, item):
  7.     num_brought = 0
  8.     for k, v in guest.items():
  9.         num_brought = num_brought + v.get(item, 0)
  10.     return num_brought
  12. print('Total brought: ')
  13. print('Apples: ' + str(total_brought(all_guests, 'apple')))
  14. print('Beer: ' + str(total_brought(all_guests, 'beer')))
  15. print('Ham: ' + str(total_brought(all_guests, 'ham')))
  16. 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:

  1. allGuests = {'Alice': {'apples': 5, 'pretzels': 12},
  2.              'Bob': {'ham sandwiches': 3, 'apples': 2},
  3.              'Carol': {'cups': 3, 'apple pies': 1}}
  5. def totalBrought(guests, item):
  6.     numBrought = 0
  7.     for k, v in guests.items():
  8.         numBrought = numBrought + v.get(item, 0)
  9.     return numBrought
  10. 	
  11. print('Number of things being brought:')
  12. print(' - Apples         ' + str(totalBrought(allGuests, 'apples')))
  13. print(' - Cups           ' + str(totalBrought(allGuests, 'cups')))
  14. print(' - Cakes          ' + str(totalBrought(allGuests, 'cakes')))
  15. print(' - Ham Sandwiches ' + str(totalBrought(allGuests, 'ham sandwiches')))
  16. print(' - Apple Pies     ' + str(totalBrought(allGuests, 'apple pies')))

My code:

  1. all_guests = {
  2.     'Alice': {'apple': 1, 'ham': 2},
  3.     'Joe': {'potato': 7, 'beer': 7},
  4.     'Carl': {'apple': 3, 'beer': 'none'}}
  6. def total_brought(guest, item):
  7.     num_brought = 0
  8.     for k, v in guest.items():
  9.         num_brought = num_brought + v.get(item, 0)
  10.     return num_brought
  12. print('Total brought: ')
  13. print('Apples: ' + str(total_brought(all_guests, 'apple')))
  14. print('Beer: ' + str(total_brought(all_guests, 'beer')))
  15. print('Ham: ' + str(total_brought(all_guests, 'ham')))
  16. print('Potato: ' + str(total_brought(all_guests, 'potato')))

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

  1. 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"：

  1. all_guests = {
  2.     'Alice': {'apple': 1, 'ham': 2},
  3.     'Joe': {'potato': 7, 'beer': 7},
  4.     'Carl': {'apple': 3, 'beer': 0}}
  6. def total_brought(guest, item):
  7.     num_brought = 0
  8.     for k, v in guest.items():
  9.         num_brought = num_brought + v.get(item, 0)
  10.     return num_brought
  12. print('Total brought:')
  13. print('Apples: ' + str(total_brought(all_guests, 'apple')))
  14. print('Beer: ' + str(total_brought(all_guests, 'beer')))
  15. print('Ham: ' + str(total_brought(all_guests, 'ham'))
  16. 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：

  1. all_guests = {
  2.     'Alice': {'apple': 1, 'ham': 2},
  3.     'Joe': {'potato': 7, 'beer': 7},
  4.     'Carl': {'apple': 3, 'beer': 'none'}}
  6. def total_brought(guest, item):
  7.     num_brought = 0
  8.     for k, v in guest.items():
  9.         val = v.get(item, 0)
  10.         if val == 'none':
  11.             val = 0
  13.         num_brought = num_brought + val
  14.     return num_brought
  16. print('Total brought:')
  17. print('Apples: ' + str(total_brought(all_guests, 'apple')))
  18. print('Beer: ' + str(total_brought(all_guests, 'beer'))
  19. print('Ham: ' + str(total_brought(all_guests, 'ham'))
  20. print('Potato: ' + str(total_brought(all_guests, 'potato'))
英文:

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

  1. 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":

  1. all_guests = {
  2.     'Alice': {'apple': 1, 'ham': 2},
  3.     'Joe': {'potato': 7, 'beer': 7},
  4.     'Carl': {'apple': 3, 'beer': 0}}
  6. def total_brought(guest, item):
  7.     num_brought = 0
  8.     for k, v in guest.items():
  9.         num_brought = num_brought + v.get(item, 0)
  10.     return num_brought
  12. print('Total brought: ')
  13. print('Apples: ' + str(total_brought(all_guests, 'apple')))
  14. print('Beer: ' + str(total_brought(all_guests, 'beer')))
  15. print('Ham: ' + str(total_brought(all_guests, 'ham')))
  16. print('Potato: ' + str(total_brought(all_guests, 'potato')))

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

  1. all_guests = {
  2.     'Alice': {'apple': 1, 'ham': 2},
  3.     'Joe': {'potato': 7, 'beer': 7},
  4.     'Carl': {'apple': 3, 'beer': 'none'}}
  6. def total_brought(guest, item):
  7.     num_brought = 0
  8.     for k, v in guest.items():
  9.         val = v.get(item, 0)
  10.         if val == 'none':
  11.             val = 0
  13.         num_brought = num_brought + val
  14.     return num_brought
  16. print('Total brought: ')
  17. print('Apples: ' + str(total_brought(all_guests, 'apple')))
  18. print('Beer: ' + str(total_brought(all_guests, 'beer')))
  19. print('Ham: ' + str(total_brought(all_guests, 'ham')))
  20. print('Potato: ' + str(total_brought(all_guests, 'potato')))

huangapple
  • 本文由 发表于 2023年3月12日 09:54:12
  • 转载请务必保留本文链接：https://go.coder-hub.com/75710657.html
  • dictionary
  • for-loop
  • function
  • nested
  • python
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