Remove a set of prefix characters from string in python

Question

I am trying to remove all the prefix "@" from the string "@@@@b@@" Expected output is "b@@" (not all the '@' but only prefix) If there is no prefix "@", it should return the original string itself This is the code, I am trying : (I am using python 2.X)

mylist = []




def remove(S):
    mylist.append(S)
    j=0
    for i in range(len(S)):
        if mylist[0][j]=='@':
            S = S[:j] + S[j + 1:]
            j+=1
            return S


        else:
            return S
            break




a = remove("@@@@b@@")

print a

What isn't working? What output are you getting? – Remolten Jun 22 '17 at 13:48 — Remolten, Jun 22 '17 at 13:48

score 7 · Accepted Answer · answered Jun 22 '17 at 13:50

7

Use lstrip()

Return a copy of the string with leading characters removed. The chars argument is a string specifying the set of characters to be removed.

>>> "@@@@b@@".lstrip("@")
'b@@'

answered Jun 22 '17 at 13:50

Christian König

3,437
16
28

score 1 · Answer 2 · answered Oct 05 '20 at 15:58

Python 3.9
There are two new string methods, removesuffix() and removeprefix()

"HelloWorld".removesuffix("World")

Output: "Hello"

"HelloWorld".removeprefix("Hello")

Output: "World"

Before Python 3.9

Using lstrip() (See Christians answer)
Be careful using lstrip and rstrip. If you are trying just to remove the first few letters. lstrip() and rstrip() will keep removing letters until it reaches an unrecognizable one.
```
  a = "@@@b@@"  
  print(a.lstrip('@@@b'))
```

Output:
Above output is a empty string, lstrip strips off everything!

a = "@@@b@@c"
print(a.lstrip('@@@b'))

Output: c

Use a regular expression

  import re
  url = 'abcdc.com'
  url = re.sub('\.com$', '', url)

`a.lstrip('@@@b')` is misleading because`lstrip` argument is a character set, not a string. Using lstrip may be convenient when the prefix is stored in a variable. https://stackoverflow.com/a/16891427/2325279 and https://stackoverflow.com/a/16891418/2325279 are both easy to read. — Petr Vepřek, Dec 01 '20 at 14:56

score 0 · Answer 3 · answered Jun 22 '17 at 13:56

0

def remove(S): return S[4:] if S.startswith('@@@@') else S
>>> remove('@@@@b@@')
'b@@'
>>> remove('@@@b@@')
'@@@b@@'

answered Jun 22 '17 at 13:56

Vitaly Instrumentov

36
2

Remove a set of prefix characters from string in python

3 Answers3