Incrementing letters

[Michael]

Hi,
I've got a string s, and i want to shift all the letters up by one, eg a->b,
b->c ........ z->a
In c++ i can do this quite simply with

if(C == 'z') C='a';
else C++;

but i can't work out how to do this this in python??

Regards

Michael

[Heiko Wundram]

Re: Incrementing letters

Am Freitag, 27. Mai 2005 13:31 schrieb Michael:[color=blue]
> if(C == 'z') C='a';
> else C++;[/color]

if C == "z":
C = "a"
else:
C = chr(ord(C)+1)

--
--- Heiko.
see you at: http://www.stud.mh-hannover.de/~hwundram/wordpress/

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[Wolfram Kraus]

Re: Incrementing letters

Heiko Wundram wrote:[color=blue]
> Am Freitag, 27. Mai 2005 13:31 schrieb Michael:
>[color=green]
>>if(C == 'z') C='a';
>>else C++;[/color]
>
>
> if C == "z":
> C = "a"
> else:
> C = chr(ord(C)+1)
>[/color]
According to the OP's problem (with the assumption that only characters
from a-z are given) he might even try a lil LC:[color=blue][color=green][color=darkred]
>>> s = "shiftthis"
>>> ''.join([chr(((ord(x)-ord('a')+1)%26) +ord('a')) for x in s])[/color][/color][/color]
'tijguuijt'


HTH,
Wolfram

[Duncan Booth]

Re: Incrementing letters

Michael wrote:
[color=blue]
> Hi,
> I've got a string s, and i want to shift all the letters up by one, eg
> a->b, b->c ........ z->a
> In c++ i can do this quite simply with
>
> if(C == 'z') C='a';
> else C++;
>
> but i can't work out how to do this this in python??[/color]
[color=blue][color=green][color=darkred]
>>> import string
>>> upone = string.maketran s([/color][/color][/color]
'abcdefghijklmn opqrstuvwxyzABC DEFGHIJKLMNOPQR STUVWXYZ',
'bcdefghijklmno pqrstuvwxyzaBCD EFGHIJKLMNOPQRS TUVWXYZA')[color=blue][color=green][color=darkred]
>>> string.translat e("I've got a string s....", upone)[/color][/color][/color]
"J'wf hpu b tusjoh t...."[color=blue][color=green][color=darkred]
>>>[/color][/color][/color]

Note the difference though: the Python code does what you said you wanted,
whereas your sample code corrupts punctuation.

[Wolfram Kraus]

Re: Incrementing letters

Duncan Booth wrote:[color=blue]
> Michael wrote:
>
>[color=green]
>>Hi,
>>I've got a string s, and i want to shift all the letters up by one, eg
>>a->b, b->c ........ z->a
>>In c++ i can do this quite simply with
>>
>>if(C == 'z') C='a';
>>else C++;
>>
>>but i can't work out how to do this this in python??[/color]
>
>[color=green][color=darkred]
>>>>import string
>>>>upone = string.maketran s([/color][/color]
>
> 'abcdefghijklmn opqrstuvwxyzABC DEFGHIJKLMNOPQR STUVWXYZ',
> 'bcdefghijklmno pqrstuvwxyzaBCD EFGHIJKLMNOPQRS TUVWXYZA')
>[color=green][color=darkred]
>>>>string.tran slate("I've got a string s....", upone)[/color][/color]
>
> "J'wf hpu b tusjoh t...."
>
>
> Note the difference though: the Python code does what you said you wanted,
> whereas your sample code corrupts punctuation.[/color]

Wow, that's quite nice. You really learn something new every day :-)
A minor improvement: Use string.ascii_le tters as the first parameter for
string.maketran s

Wolfram

[Dan Sommers]

Re: Incrementing letters

On Fri, 27 May 2005 16:10:32 +0200,
Wolfram Kraus <kraus@hagen-partner.de> wrote:
[color=blue]
> Duncan Booth wrote:[/color]
[color=blue][color=green][color=darkred]
>>>>> import string
>>>>> upone = string.maketran s([/color]
>> 'abcdefghijklmn opqrstuvwxyzABC DEFGHIJKLMNOPQR STUVWXYZ',
>> 'bcdefghijklmno pqrstuvwxyzaBCD EFGHIJKLMNOPQRS TUVWXYZA')
>>[color=darkred]
>>>>> string.translat e("I've got a string s....", upone)[/color][/color][/color]
[color=blue][color=green]
>> "J'wf hpu b tusjoh t...."[/color][/color]
[color=blue][color=green]
>> Note the difference though: the Python code does what you said you
>> wanted, whereas your sample code corrupts punctuation.[/color][/color]
[color=blue]
> Wow, that's quite nice. You really learn something new every day :-) A
> minor improvement: Use string.ascii_le tters as the first parameter for
> string.maketran s[/color]

And use string.ascii_le tters[ 1 : ] + string.ascii_le tters[ 0 ] for the
second parameter to string.maketran s.

Regards,
Dan

--
Dan Sommers
<http://www.tombstoneze ro.net/dan/>

[Simon Brunning]

Re: Incrementing letters

On 5/27/05, Michael <slick_mick_00@ hotmail.com> wrote:[color=blue]
> Hi,
> I've got a string s, and i want to shift all the letters up by one, eg a->b,
> b->c ........ z->a
> In c++ i can do this quite simply with
>
> if(C == 'z') C='a';
> else C++;
>
> but i can't work out how to do this this in python??[/color]

Here's one that works on multiple character strings, with carrying.
Rather silly, really.

<http://www.brunningonl ine.net/simon/blog/archives/001787.html>

--
Cheers,
Simon B,
simon@brunningo nline.net,

http://www.brunningonline.net/simon/blog/

[Duncan Booth]

Re: Incrementing letters

Dan Sommers wrote:
[color=blue]
> Wolfram Kraus <kraus@hagen-partner.de> wrote:
>[color=green]
>> Duncan Booth wrote:[/color]
>[color=green][color=darkred]
>>>>>> import string
>>>>>> upone = string.maketran s(
>>> 'abcdefghijklmn opqrstuvwxyzABC DEFGHIJKLMNOPQR STUVWXYZ',
>>> 'bcdefghijklmno pqrstuvwxyzaBCD EFGHIJKLMNOPQRS TUVWXYZA')
>>>
>>>>>> string.translat e("I've got a string s....", upone)[/color][/color]
>[color=green][color=darkred]
>>> "J'wf hpu b tusjoh t...."[/color][/color]
>[color=green][color=darkred]
>>> Note the difference though: the Python code does what you said you
>>> wanted, whereas your sample code corrupts punctuation.[/color][/color]
>[color=green]
>> Wow, that's quite nice. You really learn something new every day :-) A
>> minor improvement: Use string.ascii_le tters as the first parameter for
>> string.maketran s[/color][/color]

Yes, my first attempt at responding did that, but I changed it because that
makes the assumption that string.ascii_le tters is in a specific order (did
you know that lowercase came first and uppercase second without checking?)
[color=blue]
>
> And use string.ascii_le tters[ 1 : ] + string.ascii_le tters[ 0 ] for the
> second parameter to string.maketran s.
>[/color]
Bzzt. Wrong answer. Look closely at the middle of the string.

I did have:
[color=blue][color=green][color=darkred]
>>> upone = string.maketran s(string.ascii_ letters,[/color][/color][/color]
'z'+string.asci i_lowercase[:-1] +
'Z' + string.ascii_up percase[:-1])

but as I said, that makes too many assumptions for my liking about the
contents of those variables.

[Rocco Moretti]

Re: Incrementing letters

Dan Sommers wrote:[color=blue]
> On Fri, 27 May 2005 16:10:32 +0200,
> Wolfram Kraus <kraus@hagen-partner.de> wrote:
>
>[color=green]
>>Duncan Booth wrote:[/color]
>
>[color=green][color=darkred]
>>>>>>import string
>>>>>>upone = string.maketran s(
>>>
>>>'abcdefghijk lmnopqrstuvwxyz ABCDEFGHIJKLMNO PQRSTUVWXYZ',
>>>'bcdefghijkl mnopqrstuvwxyza BCDEFGHIJKLMNOP QRSTUVWXYZA')
>>>
>>>
>>>>>>string.tr anslate("I've got a string s....", upone)[/color][/color]
>
>[color=green]
>>Wow, that's quite nice. You really learn something new every day :-) A
>>minor improvement: Use string.ascii_le tters as the first parameter for
>>string.maketr ans[/color]
>
>
> And use string.ascii_le tters[ 1 : ] + string.ascii_le tters[ 0 ] for the
> second parameter to string.maketran s.
>[/color]

Not quite:
[color=blue][color=green][color=darkred]
>>> string.ascii_le tters[ 1 : ] + string.ascii_le tters[ 0 ][/color][/color][/color]
'bcdefghijklmno pqrstuvwxyzABCD EFGHIJKLMNOPQRS TUVWXYZa'

i.e. you get 'z' -> 'A' and 'Z' -> 'a'

Another issue is locale settings and special characters - what should be
done with accented letters? Preserve letter, or shift and loose accent?

[Dan Sommers]

Re: Incrementing letters

On 27 May 2005 10:52:36 -0400,
Dan Sommers <me@privacy.net > wrote:
[color=blue]
> And use string.ascii_le tters[ 1 : ] + string.ascii_le tters[ 0 ] for the
> second parameter to string.maketran s.[/color]

Oops. Thank you Duncan and Rocco for correcting my mistake.

Regards,
Dan

--
Dan Sommers
<http://www.tombstoneze ro.net/dan/>