小写和拆分输入 python 3.x

Question

I am trying to get an input() to be both lowercase and split (into separate words) and here is what I have:

commandSplit = input.split()
str.join(commandSplit)
str.lower(commandSplit)

However, I receive the error:

TypeError: descriptor 'join' requires a 'str' object but received a 'list'

Can anyone explain what the error is and how to resolve it?

Answer 1

The way I would get both lowercase and split for a string is using list comprehension.

mystr = 'This is Jamie Brinegar the novice Python programmer"
[word.lower() for word in mystr.split()] 

Answer 2

There are a few things to understand.

First, as explained by @Patrick, your usage of str.join is incorrect. The examples you copied from intended for str to be a string variable containing the delimiter you want to use to join a list of strings, ie

', '.join(['a', 'b', 'c'])

In your code above, it is unclear what the value of str is.

Second, str.lower() has a similar usage: in the examples you followed, str is intended to indicate the string you want to convert to lower-case. For example:

"A String".lower() == "a string"

Finally, as to how to solve the problem at hand, the other answers give great strategies. Essentially, convert you string to lower-case first, then split it:

input = 'Some User Input'
words = input.lower().split()
# => ['some','user','input']

Answer 3

In general you want to use the form variable.method()

I believe what you want could be done like this

commandSplit = input().split()
commandSplit = [x.lower() for x in commandSplit]

Answer 4

var = input("Enter the line\n")
word_list = var.split(' ')
word_list = [str(word).lower() for word in word_list]
print(' '.join(word_list))

The output of split function is a list type. To use join function the format is ".join(sequence_data type)" With the above code:

Input:

 String Split And Join

Output:

 string split and join

Answer 5

Other answers offered good alternative solutions, I'd like to point out the reason you get

TypeError: descriptor 'join' requires a 'str' object but received a 'list'

is because you are using an unbounded method of class str (string) without an instance as first parameter. Python permits such usage; therefore, the following 2 lines yield the same result.

str.join(", ", ["a", "b", "c"])
", ".join(["a", "b", "c"])