I would like to replace a character in a string like so, WITHOUT using the string function or anything like string.replace.
>>> replace ("banana", "a", "e")
'benene'
So for the example, I want to replace character "a" with "e" in the string "banana"
you are not really far :)
"banana".replace("a", "e")
Unless you meant, whithout using the str.replace function :) in which case here's the algorithm
def replace(str, old_char, new_char):
return ''.join([c if c != old_char else new_char for c in str])
str.join actually works faster with a list comp than a gen comp, but yuck you're shadowing str() in that function!
str.join :DSingle-character replacements are best left to str.translate():
try:
# Python 2
from string import maketrans
except ImportError:
# Python 3
maketrans = str.maketrans
def replace(original, char, replacement):
map = maketrans(char, replacement)
return original.translate(map)
str.translate() is by far the fastest option for per-character replacement mapping.
Demo:
>>> replace("banana", "a", "e")
'benene'
This supports mapping multiple characters, just make sure that both the char and replacement arguments are of equal length:
>>> replace("banana", "na", "so")
'bososo'
>>> replace("notabene", "na", "so")
'sotobese'
If for whatever reason you need to avoid using str.replace (YUCK I hate artificial requirements) you can wrap it up in a list comprehension.
NEW_CHAR = 'e'
OLD_CHAR = 'a'
''.join([NEW_CHAR if c == OLD_CHAR else c for c in "banana"])
string.replace. Or did you mean "without using the string function or anything like string.replace"? In any case, show us the code you've written so far.