From: Dave Thomas <Dave@...>
Date: 2001-04-28T03:55:45+09:00
Subject: [ruby-talk:14344] Re: array as index to array

jonas <jonas.bulow@servicefactory.se> writes:

> If a is an array, a[n] returns the n:th element. a[n..m] returns the
> n:th to the m:th element. If b is an array b=[x,y,z], it would be no
> surprise if a[b] returned the x:th, y:th and z:th element of a instead
> of:
> 
> a=(42..97).to_a
> b=[3,7,9]
> a[b]
> TypeError: failed to convert Array into Integer
> (irb):17:in `[]'
> (irb):17:in `irb_binding'
> 
> Or, what is the ruby way of doing this?

Somewhat indirectly, you can use indexes (or indices)

  a = (42..97).to_a
  b = [3, 7, 9]

  a.indexes(*b)  #=> [45, 49, 51]

However, your initial suggestion might be interesting to consider as
an RCR.


Dave