Case-insensitive string compare?

[Maric Michaud]

Le Friday 05 September 2008 14:33:22 J. Clifford Dyer, vous avez écrit :
> On Thu, 2008-09-04 at 18:48 -0500, Robert Dailey wrote:
> > Thanks everyone for your help. I'm not opposed to using [key.lower()
> > for key in stage_map] at all, I was just curious to see if there were
> > any cleaner alternatives. It looks like that is what I'll be using.
> > I'm not familiar with how python works internally, but coming from C++
> > it seems like "remaking" the map would be slow. However, speed is not
> > my main concern in my particular situation, I'm just curious to learn
> > more about python.
>
> You should be opposed to that particular solution.  You have just taken
> a dictionary lookup (very fast) and turned it into a list traversal
> (slow).  Even if speed isn't your main concern, this is an unnecessary
> de-optimization.  You are deliberately slowing down your program to
> avoid a slightly more verbose lookup later.  Your data structure might
> as well be a list of tuples to begin with, to avoid creating a new list.
> You have effectively made your keys useless as keys.
>
> If your lookups need to be case insensitive, make the key lower case,
> and store the cased version in the value, whether as a tuple or a dict
> (depending on whether you want named access).
>
> d = {
>    'foo': {'key': 'Foo', 'value': 'val1'}
>    'spam': {'key': 'sPAm', 'value': 'val2'}
> }
>
> search = 'FOO'.lower()
> if search in d:
>     result = d[search]
>     key = result['key']
>     value = result['value']
>
> The only reason I wouldn't use this solution is if you expect to have
> keys that will be identical when made lowercase, but if you're doing
> case-insensitive lookup, you obviously don't expect this to be an issue.
>

The OP has already said the keys are case-sensitive, so this is not an option, 
the only way to do it fast is to index upon insertion all keys in another 
dict, so you get in final :
d = { "kEy1" : 1, "Key1" : 2}
indexes = { "key1" : ["kEy1", "Key1" ] }

> Cheers,
> Cliff
>
>
> --
> http://mail.python.org/mailman/listinfo/python-list



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Maric Michaud