英文:
python say isalpha() is not defined despite it being built in (I think)
问题
我正在运行一个程序，该程序接收一个包含数字和字母的列表，将数字分离到一个单独的列表中并打印该列表，但每次运行代码时都会显示isalpha未定义。
yes = []
item=[1,7,-10,34,2,"a",-8]
for things in item:
if isinstance(things, str):
continue
else:
yes.append(things)
print(yes)
<details>
<summary>英文:</summary>
i am running a program that takes a list of numbers and letters, and separates the numbers into a sperate list and printing that list, but every time i run the code it says that isalpha is not defined.
yes = []
item=[1,7,-10,34,2,"a",-8]
for things in item:
if isalpha() ==True:
continue
else:
yes.append
print(yes)
</details>
# 答案1
**得分**: 1
```isalpha()``` 是 ```str``` 类的一个方法，如果字符串中的所有字符都是字母，它会返回 ```True```，否则返回 ```False```。示例：
```python
>>> MyString = "fwUBCEFèfewf"
>>> MyString.isalpha()
True
>>> MyOtherString = "f13bbG"
>>> MyOtherString.isalpha()
False
为了将项目数组中的字母和数字分开，你需要像这样重新编写代码：
letters = []
numbers = []
item = [1, 7, -10, 34, 2, "a", -8]
for things in item:
if str(things).isalpha():
letters.append(things)
else:
numbers.append(things)
print(letters)
print(numbers)
# 输出：
# ['a']
# [1, 7, -10, 34, 2, -8]
在条件内部需要使用 str(things)，因为isalpha() 只能用于字符串，而不是整数。如果不添加这个，你将会得到一个错误，错误消息为 AttributeError: 'int' object has no attribute 'isalpha'。
你也可以使用 isinstance() 函数来检查 things 是否是字符串。可以这样做：
letters = []
numbers = []
item = [1, 7, -10, 34, 2, "a", -8]
for things in item:
if isinstance(things, str) and things.isalpha():
letters.append(things)
else:
numbers.append(things)
print(letters)
print(numbers)
# 输出：
# ['a']
# [1, 7, -10, 34, 2, -8]
由于字母只能是字符串，你可以使用isinstance() 函数检查things是否是str 类型。在这种情况下，两个条件都必须为 True。
希望这能帮助你 
英文:
isalpha() is a method for the str class which returns True if all the characters inside a string are letters and False if that's not the case. Example:
>>> MyString = "fwUBCEFèfewf"
>>> MyString.isalpha()
True
>>> MyOtherString = "f13bbG"
>>> MyOtherString.isalpha()
False
In order to separate all the letters and numbers inside the item array you need to rewrite your code like this:
letters = []
numbers = []
item=[1,7,-10,34,2,"a",-8]
for things in item:
if str(things).isalpha():
letters.append(things)
else:
numbers.append(things)
print(letters)
print(numbers)
# output:
# ['a']
# [1, 7, -10, 34, 2, -8]
You will have to do str(things) inside the conditions because the isalpha() is only a function you can use on strings and not integers. If you don't add this you will get an error saying AttributeError: 'int' object has no attribute 'isalpha'.
You could also do this if you use the isinstance() function to check wether things is a string or not. You would do it like this:
letters = []
numbers = []
item=[1,7,-10,34,2,"a",-8]
for things in item:
if isinstance(things, str) and things.isalpha():
letters.append(things)
else:
numbers.append(things)
print(letters)
print(numbers)
# output:
# ['a']
# [1, 7, -10, 34, 2, -8]
Since the letters can only be strings you can check if the things is of type str with the isinstance() function. Here two conditions have to be True.
I hope that I could help you
答案2
得分: 0
.isalpha 是一个方法而不是一个函数 <sup>（查看此教程 以了解更多区别）</sup>，因此不能按名称调用。我认为您想要
if str(things).isalpha(): continue
或者
if isinstance(things, str) and things.isalpha():
continue
<br>
另外，在 continue 后面不需要 else，所以可以继续使用 yes.append(things) <sup>（而不仅仅是 yes.append)</sup>:
yes = []
item=[1,7,-10,34,2,"a",-8]
for things in item:
if isinstance(things, str) and things.isalpha():
continue
yes.append(things)
print(yes)
（但为什么您要在循环内部而不是在循环之后打印 yes [可能重复]？）
或者，您可以只是使用 列表推导 <sup>（查看输出）</sup>
item=[1,7,-10,34,2,"a",-8]
yes = [i for i in item if not (isinstance(i, str) and i.isalpha())]
print(*yes, sep='\n')
英文:
.isalpha is a method not a function <sup>(see this tutorial to learn more about the difference)</sup>, so it cannot be called by name. I think you want
if str(things).isalpha(): continue
or
if isinstance(things, str) and things.isalpha():
continue
<br>
Also, the else is not necessary after continue, so you can follow with yes.append(things) <sup>(not just yes.append)</sup>:
yes = []
item=[1,7,-10,34,2,"a",-8]
for things in item:
if isinstance(things, str) and things.isalpha():
continue
yes.append(things)
print(yes)
(But why are you printing yes [potentially on repeat] inside the loop instead of after the loop?)
Alternately you could just use list comprehension <sup>(view output)</sup>
item=[1,7,-10,34,2,"a",-8]
yes = [i for i in item if not (isinstance(i, str) and i.isalpha())]
print(*yes, sep='\n')
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