From: Robert Klemme <shortcutter@...>
Date: 2012-05-07T23:18:41+09:00
Subject: Re: Why Enumerator#next does not return more than one value?

On Mon, May 7, 2012 at 3:10 PM, Földes László <lists@ruby-forum.com> wrote:
> If I have an Enumerator which yields elements of a mathematical series
> (logistic map), I can use:
>
> enum.first(10) to get the first 10 value,
> enum.next to get the next values,
>
> but there is no enum.next(10) to get the next 10 values.
> I do some trickery like this to achieve the same result (because I need
> the result in an Array, as #first returns it):
> (0..20).map {(lm.next)}
>
> Is there a nicer way to do it? (Or did I overlook some existing method
> in Enumerable?)

Question is: what do you need that for?

> At first I thought it is logical that #next should have a parameter so
> the #first(10) method could be actually a #rewind + #next(10).

If you need chunks of the same size #each_slice is the proper method to use.

irb(main):015:0> 10.times.each_slice(3).to_a
=> [[0, 1, 2], [3, 4, 5], [6, 7, 8], [9]]

Note: there's also #each_cons

irb(main):017:0> 10.times.each_cons(7).to_a
=> [[0, 1, 2, 3, 4, 5, 6], [1, 2, 3, 4, 5, 6, 7], [2, 3, 4, 5, 6, 7,
8], [3, 4, 5, 6, 7, 8, 9]]

Kind regards

robert

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