Am I programming in Python mode?

Mordy Ovits movits at lockstar.com
Wed Feb 2 16:29:38 CET 2000


Michael Hudson wrote:
> 
> Anders M Eriksson <anders.eriksson at morateknikutveckling.se> writes:
> 
> > Hello!
> >
> > Being new to Python I would like your comments on this function. Is it
> > written in Pytnon mode?
> 
> Only you can tell if it was written in Python mode ('round here Python
> mode usually refers to the emacs major mode for Python). I can try and
> help with style, which is what I'm fairly sure you meant.
> 
> > The function returns a random string, and have 3 params the lenght of
> > the string, lowercase/Uppercase and dublicates
> >
> > Any comments and/or suggestions are welcome!!
> >
> > // Anders
> >
> >
> >
> > def randStr(n, lower=1, dublicates=1):
> >     # returns a random string with <n> characters
> >     # lower         if true only lowercase letters
> >     # dublicates    if true then the same letter can be repeated
> 
> This bit could (should) be in a docstring, not a comment.
> 
> >     if lower:
> >         l = ord('a')
> >         h = ord('z')
> >     else:
> >         l = ord('A')
> >         h = ord('z')
> 
> Hmm, does this actually work? ASCII goes like:
> 
> .... STUVWXYZ[\]^_`abcdefghijk ...
> 
> so the above will get strings containing [\]^_` characters.
> 
> >     str = ""
> >     generator = whrandom.whrandom()
> 
> Why do you want your on generator?
> 
> >     for i in range (n):
> >         ch = generator.randint(l,h)
> >         if dublicates:
> >             str = str + chr(ch)
> 
> It's probably better to accumulate substrings into a list and use
> string.join to stick them together. This is particularly true in the
> single character case, 'cause they're cached.
> 
> >         else:
> >             bRepeat = 1
> >             while bRepeat:
> >                 if not chr(ch) in str:
> >                     str = str + chr(ch)
> >                     bRepeat = 0
> >                 else:
> >                     ch = generator.randint(l,h)
> >
> >
> >     return str
> 
> You do know about random.choice don't you? It selects a random item
> from a sequnce - and strings are sequences.
> 
> So if I were doing this I'd do it like this:
> 
> import random,string
> 
> def randStr(n,lower=1,duplicates=1):
>     """ randStr(n:Integer[,lower,duplicates]) -> String
> 
> Generate a random string of length n.
> If |lower| is true (the default), only lowercase letters will be used.
> If |duplicates| is true (the default), the string may contain duplicates. """
>     if lower:
>         choices = 'abcdefghijklmnopqrstuvwxyz'
>     else:
>         choices = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'
>     result = []
>     if not duplicates and n > len(choices):
>         raise ValueError, "n too large"
>     for i in range(n):
>         while 1:
>             ch = random.choice(choices)
>             if duplicates or ch not in result:
>                 result.append( ch )
>                 break
>     return string.join(result,'')
> 
> This probably isn't perfect, but I hope in helps.
> 
> Cheers,
> Michael

See string.lowercase, string.uppercase and string.letters


As in:

for i in range(0, n):
   string.append(random.choice(string.letters))


Mordy
-- 
o Mordy Ovits
o Cryptographic Engineer
o LockStar, Inc.
--
There are two kinds of fool; One who says "This is old
and therefore bad," and one who says "This is new and
therefore better." -- John Brunner



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