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
– Remolten

2017-06-22 13:48:48 +00:00
Commented Jun 22, 2017 at 13:48 — Remolten
– Remolten, Commented Jun 22, 2017 at 13:48
Simply do a.lstrip('@').

ForceBru
– ForceBru

2017-06-22 13:50:16 +00:00
Commented Jun 22, 2017 at 13:50 — ForceBru
– ForceBru, Commented Jun 22, 2017 at 13:50

Christian König · Accepted Answer · 2017-06-22 13:50:04Z

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, 2017 at 13:50

Christian König

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Comments

John Salzman · Accepted Answer · 2020-10-05 15:58:32Z

1

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)

answered Oct 5, 2020 at 15:58

John Salzman

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1 Comment

Petr Vepřek Over a year ago

a.lstrip('@@@b') is misleading becauselstrip argument is a character set, not a string. Using lstrip may be convenient when the prefix is stored in a variable. stackoverflow.com/a/16891427/2325279 and stackoverflow.com/a/16891418/2325279 are both easy to read.

Vitaly Instrumentov · Accepted Answer · 2017-06-22 13:56:12Z

0

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

answered Jun 22, 2017 at 13:56

Vitaly Instrumentov

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