From: Daniel Berger <djberg96@...>
Date: 2006-10-05T00:10:13+09:00
Subject: Re: Equvialent of Python slices?

Logan Capaldo wrote:
> On Wed, Oct 04, 2006 at 11:10:10PM +0900, Daniel Berger wrote:
> >
> > James Edward Gray II wrote:
> > > On Oct 4, 2006, at 8:19 AM, Peter Szinek wrote:
> > >
> > > > Hello,
> > > >
> > > > Sorry for the lame question again, but even after a lot of googling
> > > > I still couldn't find the $subj., ie. something like:
> > > >
> > > > >>> "asdfghj"[2::2]
> > > > 'dgj'
> > > > (= every second letter, beginning from the 2nd index in the string)
> >
> > Interesting, though I'm surprised Python has explicit syntax for what
> > seems like a highly specific type of operation.  But, hey, cool.
> >
> > > I'm not going to call this as pretty, of course, but:
> > >
> > >  >> test = "asdfghj"
> > > => "asdfghj"
> > >  >> test[2..-1].gsub(/(.)./, "\\1")
> > > => "dgj"
> >
> > Slightly OT here....
> >
> > I'm trying to remember why test[2, -1] returns nil.  Positive numbers
> > for the second integer work as expected:
> >
> > test[2,1] => 'd'
> > test[2,2] => 'df'
> > test[2,100] => dfghj
> > test[2,-1] => nil
> I can see it logically, test[start position, length]. A negative one
> length doesn't make much sense. test[2..-1] works though, since it's
> start postion..(.)end position. Unfortunately you can't coun't backwards
> with a negative length ( like if I want the last two characters I can't
> say test[-1, -2]. )

Ok, I just need to remember the second value is a length, not an index,
although that still confuses me.

I wonder if making that change would cause havoc with the regex engine.
 Best to leave it alone I suppose.

Regards,

Dan