Don't understand, what it means : TypeError: can only concatenate str (not "list") to str

Question

在开始描述问题之前，我需要说明一下，英语不是我的母语，因此，不幸的是，我可能会犯很多错误。感谢理解！

favourite_places = {
    'Paris':['Jake','Carl'],
    'London':'Jake',
    'Moscow':'Fred',
 }

for username,user_info in favourite_places.items():
    
print('======================')
    
print('Place: ' + username)
    
print('Who likes it: ' + user_info)

错误：

Type of error: TypeError: can only concatenate str (not "list") to str

我现在真的不知道该如何解决。当我清除 ['Carl'] 时，程序开始工作，但我需要 ['Carl']。请帮助

Answer 1

您正在尝试打印“谁喜欢它：[杰克，卡尔]”

不出所料，python 不喜欢这样...

试试这个：

favourite_places = {
'Paris':['Jake','Carl'],
'London':['Jake'],
'Moscow':['Fred'],
 }

for username,user_info in favourite_places.items():

    print('======================')

    print('Place: ' + username)
    
    users = ""
    for user in user_info:
        users = users + user + ", "
    users = users[:len(users)-2]   #Ach, sure we'll stick this in too to clean up the last trailing comma & space we don't want

    print('Who likes it: ' + users)

Answer 2

制作所有字典值列表，以便在需要时可以将它们全部连接起来：

favourite_places = {
    'Paris': ['Jake','Carl'],
    'London': ['Jake'],
    'Moscow': ['Fred'],
 }

然后当您需要打印列表时，使用 f 字符串：

print(f'Who likes it: {user_info}')

Answer 3

将您的列表项加入一个字符串：

favourite_places = {
    'Paris':['Jake','Carl'],
    'London':['Jake'],
    'Moscow':['Fred']
 }

for username,user_info in favourite_places.items():
    print('======================')
    print('Place: ' + username)
    print('Who likes it: ' + ', '.join(user_info))

Answer 4

错误语句说明了一切：您只能将 str（而不是“列表”）连接到 str。

您应该更改您的字典，以便每个值都是一个列表，以便使用一致的数据。

但是，采用懒惰的方式，您可以也可以像下面最后一行那样简单地使用 f-string :

for username,user_info in favourite_places.items():
    print('======================')
    print('Place: ' + username)
    print(f"Who likes it: {user_info}")

输出：

======================
Place: Paris
Who likes it: ['Jake', 'Carl']
======================
Place: London
Who likes it: Jake
======================
Place: Moscow
Who likes it: Fred

Don't understand, what it means : TypeError: can only concatenate str (not "list") to str

Don't understand, what it means : TypeError: can only concatenate str (not "list") to str

python

typeerror