From: gwtmp01@...
Date: 2006-09-14T00:54:29+09:00
Subject: Re: arbitrary indexes


On Sep 12, 2006, at 12:18 PM, Austin Ziegler wrote:

> On 9/12/06, Jason Nordwick <jason@adapt.com> wrote:
>> There has to be an easier way to do this.
>>
>> If I have v=(1..99).to_a and I want to index the 20th to 30th  
>> elements, this is simply v[20,10]. But if I have a list of indexes  
>> i=[9, 11, 35, 47, 48, 55, 58, 63, 92, 96] that I want, I can't  
>> seem to find a simpler way than i.map{|x|v[x]} which seem like an  
>> aweful lot of syntax just for what is essentially "v[i]". Is there  
>> an easier way to do this?
>
>>> v.values_at(9, 11, 35, 47, 48, 55, 58, 63, 92, 96)
> => [10, 12, 36, 48, 49, 56, 59, 64, 93, 97]

Another nice thing about values_at is that it understands ranges:

a = Array.new(10) { |x| x*2 }	#=> [0, 2, 4, 6, 8, 10, 12, 14, 16, 18]

b = a.values_at(1,3,5..7)	#=> [2, 6, 10, 12, 14]


Gary Wright