How do I replace all instances of the first letter in a string, but not the first letter itself

Question

My code so far is:

def ChangeString():
    print (userString.replace(
userString =str(input("Please enter a string "))
ChangeString()

In a string, I need to replace all instances of the first character with a *, without actually replacing the first character itself. An example is, let's say I have "Bobble"; the function would return something like, "Bo**le".

Dude, I'm learning; I have no idea how to do it, that's why I asked the question — The White Wolf, Oct 13 '15 at 19:52
I get that you are learning, but dont you feel like just seeing if the code compiles once ?? — karthikr, Oct 13 '15 at 19:55

score 1 · Answer 1 · answered Oct 13 '15 at 19:50

1

>>> test = 'Bobble'    
>>> test = test[0] +''.join(l if l.lower() != test[0].lower() else '*' for l in test[1:])
>>> print test

Bo**le

answered Oct 13 '15 at 19:50

xiº

4,605
3
28
39

score 1 · Accepted Answer · answered Oct 13 '15 at 19:52

1

userString[0] + userString[1:].replace(userString[0], "*")

answered Oct 13 '15 at 19:52

P.Melch

8,066
43
40

but this solution is actually case sensitive... :( – P.Melch Oct 13 '15 at 19:54
Thanks, that worked fine. Yh, the case sensitivity is sort of a problem, but I'll try figure it out. – The White Wolf Oct 13 '15 at 20:20

Padraic Cunningham · Answer 3 · 2015-10-13T20:26:47.963

You could also use a regex:

import re

def ign_first(s, repl):
    return re.sub(r"(?<!^){}".format(s[0]), repl, s, flags=re.I)

Demo:

In [5]: s = "Bobble"

In [6]: ign_first(s, "*")
Out[6]: 'Bo**le'

Or use str.join with a set:

def ign_first(s, repl):
    first_ch = s[0]
    st = {first_ch, first_ch.lower()}
    return first_ch + "".join([repl if ch in st else ch for ch in s[1:]])

Demo:

In [10]: ign_first(s, "*")
Out[10]: 'Bo**le'

score 0 · Answer 4 · answered Oct 13 '15 at 19:53

0

I would use slices and lower().

>>> test = 'Bobble'
>>> test[0] + test[1:].lower().replace(test[0].lower(), '*')
'Bo**le'

answered Oct 13 '15 at 19:53

BlivetWidget

10,543
1
14
23

score 0 · Answer 5 · answered Oct 13 '15 at 19:54

0

There's no need to use additional variables

>>> st='Bobble'
>>> st=st[0]+st[1:].lower().replace(st[0].lower(),'*')
>>> st
'Bo**le'

answered Oct 13 '15 at 19:54

ForceBru

43,482
10
63
98

Jose Haro Peralta · Answer 6 · 2015-10-13T20:39:12.980

0

case-insensitive solution with regular expressions:

import re

string = "Bobble"

outcome = string[0]+re.sub(string[0].lower() + '|' + string[0].upper(), 
                           "*", string[1:].lower())

>>>
Bo**le

edited Oct 13 '15 at 20:39

answered Oct 13 '15 at 20:25

Jose Haro Peralta

969
7
14

1

You will also end up changing all the string to lower, the replacement should be case insensitive but that does not mean every letter is lowercase – Padraic Cunningham Oct 13 '15 at 20:32
Thank you for the observation Padraic! I edited my answer. It should work now. All occurrences of the first letter are substituted in the word, no matter whether they are upper or lower case, without changing the original string. – Jose Haro Peralta Oct 13 '15 at 20:41
I just saw that you actually posted the same solution shortly before me ^^" haha, sorry for the duplication – Jose Haro Peralta Oct 13 '15 at 20:43
You would need re.I. if you had an uppercase letter in the string like the first lettter of a name, place etc..you would also lower that. The logic needs to do a case insensitive replacement but leave the rest of the string as is. – Padraic Cunningham Oct 13 '15 at 20:54

How do I replace all instances of the first letter in a string, but not the first letter itself

6 Answers6