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

 

[Wolfram Kraus]

Am Freitag, 27. Mai 2005 13:31 schrieb Michael:



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

According to the OP's problem (with the assumption that only characters
from a-z are given) he might even try a lil LC:

>>> s = "shiftthis"
>>> ''.join([chr(((ord(x)-ord('a')+1)%26)+ord('a')) for x in s])

'tijguuijt'


HTH,
Wolfram

 

[Duncan Booth]

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??

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

 

[Heiko Wundram]

Am Freitag, 27. Mai 2005 13:31 schrieb Michael:

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

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]

Michael wrote:



"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.

Wow, that's quite nice. You really learn something new every day
A minor improvement: Use string.ascii_letters as the first parameter for
string.maketrans

Wolfram

 

[Dan Sommers]

Duncan Booth wrote:

Wow, that's quite nice. You really learn something new every day A
minor improvement: Use string.ascii_letters as the first parameter for
string.maketrans

And use string.ascii_letters[ 1 : ] + string.ascii_letters[ 0 ] for the
second parameter to string.maketrans.

Regards,
Dan

 

[Simon Brunning]

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??

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

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

 

[Duncan Booth]

Yes, my first attempt at responding did that, but I changed it because that
makes the assumption that string.ascii_letters is in a specific order (did
you know that lowercase came first and uppercase second without checking?)

And use string.ascii_letters[ 1 : ] + string.ascii_letters[ 0 ] for the
second parameter to string.maketrans.

Bzzt. Wrong answer. Look closely at the middle of the string.

I did have:
'z'+string.ascii_lowercase[:-1] +
'Z' + string.ascii_uppercase[:-1])

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

 

[Rocco Moretti]

Duncan Booth wrote:


Wow, that's quite nice. You really learn something new every day A
minor improvement: Use string.ascii_letters as the first parameter for
string.maketrans

And use string.ascii_letters[ 1 : ] + string.ascii_letters[ 0 ] for the
second parameter to string.maketrans.

Not quite:

>>> string.ascii_letters[ 1 : ] + string.ascii_letters[ 0 ]

'bcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZa'

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]

And use string.ascii_letters[ 1 : ] + string.ascii_letters[ 0 ] for the
second parameter to string.maketrans.

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

Regards,
Dan