如何删除字符串中的所有内容，直到在 Python 中看到一个或多个字符

Question

Say I have a string and I want to remove the rest of the string before or after certain characters are seen

For example, all my strings have 'egg' in them:

"have an egg please"
"my eggs are good"

I want to get:

"egg please"
"eggs are good"

and also the same question but how can I delete all but the string in front of the characters?

Answer 1

You can use str.find method with a simple indexing :

>>> s="have an egg please"
>>> s[s.find('egg'):]
'egg please'

Note that str.find will returns -1 if it doesn't find the sub string and will returns the last character of your string.So if you are not sure that always your string is contain the sub string you better to check the value of str.find before using it.

>>> def slicer(my_str,sub):
...   index=my_str.find(sub)
...   if index !=-1 :
...         return my_str[index:] 
...   else :
...         raise Exception('Sub string not found!')
... 
>>> 
>>> slicer(s,'egg')
'egg please'
>>> slicer(s,'apple')
Sub string not found!

Answer 2

string = 'Stack Overflow'
index = string.find('Over') #stores the index of a substring or char
string[:index] #returns the chars before the seen char or substring

Hence, the output will be

'Stack '

and

string[index:]

will give

'Overflow'

Answer 3

use regular expression to fetch the sub string.

import re
def slice(str, startWith):
    m = re.search(r'%s.*' % startWith,str) # to match pattern starts with `startWith`
    if not m: return ""#there is no proper pattern, m is None
    else: return m.group(0)

Answer 4

您可以使用str.join()和str.partition() ：

''.join('have an egg please'.partition('egg')[1:])

Answer 5

>>> s = "eggs are good"
>>> word = "eggs"
>>> if word in s:
        print s.split(word)[1]
are good