[Tutor] Fw: list.replace -- string.swap

[ALAN GAULD]

It wasn't my question :-)

Forwarding to list...

 
Alan Gauld
Author of the Learn To Program website
http://www.alan-g.me.uk/




----- Original Message ----
> From: Ricardo Aráoz <ricaraoz at gmail.com>
> Subject: Re: [Tutor] Fw:  list.replace -- string.swap
> 
> 
> >>>> Also: How would perform string.swap(s1, s2) in the following cases:
> >>>>        
> >> Here I mean exchanging s1 and s2 occurrences all along a string. As an 
> example, 
> >> in a text containing numerous formatted numbers, switch from english to 
> european 
> >> format:
> >>    1,234,567.89
> >>    1.234.567,89
> >> meaning exchange '.' and ','.
> >>
> >>    
> >>>> * There is no secure 'temp' char, meaning that
> >>>> s.replace(s1,temp).replace(s2,s1).replace(temp,s2)
> >>>>  will fail because any char can be part of s.
> >>>>        
> >> The use of a temp char for marking places of one the chars to be swapped is a 
> 
> >> common trick. But if the text can contain any char (even chr(0)), then there 
> no 
> >> char you can safely use as temp.
> >> The only workaround I know is to pass through lists. Then swap on the list, 
> >> using eg None as temp item, and glue back the result to a string. But you 
> need 
> >> them a replace method on lists, hence my previous question ;-)
> >>
> >>    
> >>>> * Either s1 or s2 can be more than a single char.
> >>>>        
> >> More difficult, cause you cannot simple list() the string. It must split on 
> s1 
> >> and s2, but keeping the delimiters! There is no option afaik for that in 
> >> string.split -- too bad! So that you must split it manually at start and end 
> of 
> >> each instance of s1 and s2. Or there are other algorithms I cannot figure 
> out. 
> >> What I was asking for.
> >>    
> 
> So NOW I get your question!!!
> It's easy :
> 
> >>> import string
> >>> mystr = '1,234,567.89'
> >>> mystr.translate(string.maketrans('.,', ',.'))
> '1.234.567,89'
> 
> Any length of string to be translated, any length of translation tables
> (not only two values, any amount of them).
> 
> HTH
> 
> Ricardo.