From: Robert Klemme <shortcutter@...>
Date: 2007-03-09T18:32:50+09:00
Subject: Re: 2 lines in one...

2007/3/9, Josselin <josselin@wanadoo.fr>:
> Could I write it in just 1 line ?
>
> find the first value greater than d, in a list (special one :  each
> value is the double of the previous...)
> then give me the index of this value (with special case ...)
>
>       i =
> ([0.5,1.0,2.0,4.0,8.0,16.0,32.0,64.0,128.0,256.0,512.0,1024.0,2048.0].select
> {|v| v if v >= d }).first
>
>       zl = d <0.5  ? 0 :
> [0.5,1.0,2.0,4.0,8.0,16.0,32.0,64.0,128.0,256.0,512.0,1024.0,2048.0].index(i)

irb(main):015:0>
arr=[0.5,1.0,2.0,4.0,8.0,16.0,32.0,64.0,128.0,256.0,512.0,1024.0,2048.0]
=> [0.5, 1.0, 2.0, 4.0, 8.0, 16.0, 32.0, 64.0, 128.0, 256.0, 512.0,
1024.0, 2048.0]
irb(main):016:0> idx = arr.to_enum(:each_with_index).inject(nil)
{|x,(e,i)| break i if e > 100}
=> 8
irb(main):017:0> idx = arr.to_enum(:each_with_index).inject(nil)
{|x,(e,i)| break i if e > 1000000}
=> nil

Kind regards

robert

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