Question

我在Python 3.3中有一个程序，它有一个字符串，我想把这些东西放到最后。例如＆＃34;玛丽有一只小羊羔＆＃34;。我想在＆＃39; a＆＃39;之后得到文字。在字符串中。我怎么能这样做？

Answer 1

s =  "Mary had a little lamb"
print(s.split(" a ")[1])
little lamb
print (s[10:])
little lamb`

在a上拆分并获取10th字符之后或切片到字符串末尾的元素。

s =  'Mary had a very very little lamb'
print(s.split(" a ",1)[1]) 

very very little lamb

如果你有两个潜在的字符串之一：

sts = ["Mary had some little lamb","Mary had a little lamb"]
for s in sts:
    if " a " not  in sts:
        print("a is not in this string so the result is {}".format(s.split("had",1)[1]))
    else:
        print("a is in this string so  the result is {}".format(s.split(" a ",1)[1]))

如果您只想将最后两个单词作为字符串：

sts = ["Mary had some little lamb","Mary had a little lamb"]
for s in sts:
    print(" ".join(s.split()[-2:])) # from second last element to the end
little lamb
little lamb

如果您有一个包含两个" a "的字符串，并且想要仅拆分最后一个字符串：

s =  "Mary had a dog and  a little lamb"
print(s.rsplit(" a ",1)[1]) # use rsplit in maxsplit = 1, to only split once
little lamb

如果你有复杂的搜索模式，那么re可能就是你需要的。

Answer 2

使用切片方法。

result = mystring[start:end]

开始是包容性的，结束是独家的。

mystring = "Mary had a little lamb"
newstring = mystring[11:]
print(newstring)
>>> "little lamb"

如果您没有发布的开始或结束数字，则会从最开始或结束时开始。

编辑：根据你上面的评论答案：你可以做这样的事情

>>> mystring = "Mary had a very little lamb"
>>> mystring2 = "Mary had little little lamb"
>>> strings = [mystring, mystring2]
>>> for string in strings:
        if string[9] == 'a':
            newstring = string[11:]
        else:
            newstring2 = string[9:]
>>> newstring
'very little lamb'
>>> newstring2
'little little lamb'

这是假设总有一个＆＃34;玛丽有......＆＃34;在你的字符串的开头，并将抓住＆＃34; a＆＃34;之后的内容。如果有或没有。这不是我不会想到的最佳解决方案，但会为您提供一种思考方式。

如何从Python中提取我想要的字符串

2 个答案: