Replace characters in string from dictionary mapping

python string dictionary replace

15,618

Solution 1

Translations are way faster.

>>> import string
>>> text.translate(string.maketrans("".join(restAlphaSet),"".join(item)))

Solution 2

You are overlooking the translate function. See here for a usage example.

15,618

Author by

NickG

Updated on June 23, 2022

Comments

NickG almost 2 years
I'm pretty new to python, so forgive me if I am missing an obvious built-in function.

I have a dictionary mapping I generated like the following:
```
dictionary = dict(zip(restAlphaSet,list(item)))
```
where restAlphaSet it a string and list(item) is list converted iteration

I am trying to use this to replace all the characters in my string. I found a replaceAll function online that looks like the following:
```
def replace_all(text, dic):
for i, j in dic.iteritems():
    if i != j:
        text = text.replace(i, j)
return text
```
Unfortunately, this is flawed as if the mapping has a->b, b->a, then nothing would get changed as the b's would be changed back to the a's.

I found the translate function, but it doesn't accept a dictionary input.
- cfedermann about 12 years
  
  What about removing the b -> a mappings?
- Joel Cornett about 12 years
  
  There's a syntax error in your example function. If i!=j needs a colon at the end, else it will generate a SyntaxError.
- Lev Levitsky about 12 years
  
  First it will fail with IndentationError :)
- NickG about 12 years
  
  its very similar to a cryptogram. So letters can be mapped to any other letter (no dupliactes), I just need an order independent function. And ya I copied bad, i'll add colon
- georg about 12 years
  
  translate does accept dicts if applied to unicode objects (see docs.python.org/library/stdtypes.html#str.translate)
- Gareth Latty about 12 years
  
  Who cares if translate accepts dicts? You made a dict because that was what you needed, if you don't, just use your lists to construct a translation table.
NickG about 12 years

it seems the translate function has the same issue as before where it is changing characters back to what they were.
luke14free about 12 years

@NickG mm.. it must be an issue with your code, post it so that we can figure out what's the problem.
mirek over 3 years

Py 3.x?, sure 3.9+: str.maketrans (no need to import).
mirek over 3 years

str.maketrans (don't import: string)