How to extract the first and final words from a string?

问题

I have a small problem with something I need to do in school...

My task is the get a raw input string from a user (text = raw_input()) and I need to print the first and final words of that string.

Can someone help me with that? I have been looking for an answer all day...

回答1:

You have to firstly convert the string to list of words using str.split and then you may access it like:

>>> my_str = "Hello SO user, How are you"
>>> word_list = my_str.split()  # list of words

# first word  v              v last word
>>> word_list[0], word_list[-1]
('Hello', 'you')

From Python 3.x, you may simply do:

>>> first, *middle, last = my_str.split()

回答2:

If you are using Python 3, you can do this:

text = input()
first, *middle, last = text.split()
print(first, last)

All the words except the first and last will go into the variable middle.

回答3:

Let's say x is your input. Then you may do:

 x.partition(' ')[0]
 x.partition(' ')[-1]

回答4:

You would do:

print text.split()[0], text.split()[-1]

回答5:

Some might say, there is never too many answer's using regular expressions (in this case, this looks like the worst solutions..):

>>> import re
>>> string = "Hello SO user, How are you"
>>> matches = re.findall(r'^\w+|\w+$', string)
>>> print(matches)
['Hello', 'you']

回答6:

Simply pass your string into the following function:

def first_and_final(str):
    res = str.split(' ')
    fir = res[0]
    fin = res[len(res)-1]
    return([fir, fin])

Usage:

first_and_final('This is a sentence with a first and final word.')

Result:

['This', 'word.']

来源：https://stackoverflow.com/questions/41228115/how-to-extract-the-first-and-final-words-from-a-string

标签

python

string

split

extract