How can I replace multiple characters in a string using python?

Question

I am having some trouble figuring out how to replace multiple characters in a string.I am trying to write a functions called replace(string) that takes in an input, and replaces certain letters in the input with another letter.

Lets say I have the string "WXYZ" and I want to replace all the W with Y, X with Z, Y with W, and Z with X. I want it to do the replacement no matter what the input is. so if I also do something like replace("WWZXWWXYYZWYYY") it should replace the letters like I said above.

This is what I have done so far:

def replace(string):
for letters in string:
 string = string.replace("W","Y").replace("X","Z").replace("Y","W").replace("Z","X")
print(string)

but when I run it with replace("WXYZ")

I get the output of the code as: WXWX

Instead of getting YZWX as the output. I also want to use the built in functions of python as well. Can someone help me figure this out, thank you!

• cs95: str.translate would be the way to go.
• Aran-Fey: Related: Python string replace two things at once?

Answer 1

Note that your calls are structured in such a way that W is replaced with Y in the first call, and then Y is again replaced with W in the third call, undoing the first call's output.

You should be using str.translate, it's much more efficient and robust than a bunch of chained replace calls:

_tab = str.maketrans(dict(zip('WXYZ', 'YZWX')))
def replace(string):
 return string.translate(_tab)

---

>>> replace('WXYZ')
'YZWX'
>>> replace("WWZYWXXWYYZW")
'YYXWYZZYWWXY'