From: Ross Bamford <rossrt@...>
Date: 2006-03-02T01:48:56+09:00
Subject: Re: Indexing system - ruby newbie

On Thu, 2006-03-02 at 01:42 +0900, Peter Ertl wrote:
> how about that?
> 
> (n < 1) ? "_" : (("A"[0] + n).chr)
> 
> n = 12
> > M
> 

n = 27
> \

OP wanted:

 ...  24   25   26   27    28    29   ...
 ... 'X', 'Y', 'Z', 'AA', 'AB', 'AC' ...

> 
> 
> > --- Urspr端ngliche Nachricht ---
> > Von: Ross Bamford <rossrt@roscopeco.co.uk>
> > An: ruby-talk@ruby-lang.org (ruby-talk ML)
> > Betreff: Re: Indexing system - ruby newbie
> > Datum: Thu, 2 Mar 2006 01:37:06 +0900
> > 
> > On Thu, 2006-03-02 at 00:14 +0900, Adam Groves wrote:
> > > Dear Ross,
> > > 
> > > it works a treat but I'm having a bit of trouble figuring out what's 
> > > going on.
> > > 
> > >  	  (n < 1) ? '_' : (1...n).inject("A") { |curr, i| curr.succ }
> > > 
> > > I get this:
> > > if n<1
> > >   '_'
> > > else
> > > 
> > > But I'm stuck here.
> > > 
> > >   (1...n).inject("A") { |curr, i| curr.succ}
> > > 
> > > I still can't quite get my head around blocks beyond .each do |x|
> > 
> > Inject is real easy, and very handy. It's just like 'each', except it
> > also allows the result of the previous iteration to be injected via the
> > first argument. For the first iteration, you provide the initial result.
> > 
> > For example:
> > 
> > 	a = [1,2,3,4,5]
> > 
> > 	a.inject(0) { |sum, i| sum + i }
> > 	# => 15
> > 
> > What happens is:
> > 
> > 	Block is called with sum = 0, i = 1
> > 	  Block returns 1
> > 	Block is called with sum = 1, i = 2
> > 	  Block returns 3
> > 	Block is called with sum = 3, i = 3
> > 	  Block returns 6
> > 	Block is called with sum = 6, i = 4
> > 	  Block returns 10
> > 	Block is called with sum = 10, i = 5
> > 	  Block returns 15
> > 	No more elements, so inject returns 15.
> > 
> > In Ruby, inject allows you to omit the initial value, in which case the
> > first _two_ elements from the enumerable are passed to the first
> > iteration, with things proceeding as above from there, so I could have
> > written:
> > 
> > 	a.inject { |sum, i| sum + i }
> > 
> > And would have:
> > 
> > 	Block is called with sum = 1, i = 2
> > 	  Block returns 3
> > 	Block is called with sum = 3, i = 3
> > 	  Block returns 6
> > 	.
> > 	.
> > 	etc.
> > 
> > You can use inject for much more than just summing stuff up. Comes in
> > very handy for these cryptic one-lines (even if you have to 'misuse' it
> > a bit occasionally).
> > 
> > -- 
> > Ross Bamford - rosco@roscopeco.REMOVE.co.uk
> > 
> > 
> 
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-- 
Ross Bamford - rosco@roscopeco.REMOVE.co.uk