From: Todd Benson <caduceass@...>
Date: 2007-08-31T09:09:50+09:00
Subject: Re: How to make an array of hashes to a single array with all the values of these hashes ?

On 8/30/07, Robert Klemme <shortcutter@googlemail.com> wrote:
> On 30.08.2007 16:47, Todd Benson wrote:
> > On 8/30/07, Robert Klemme <shortcutter@googlemail.com> wrote:
> >> 2007/8/29, yermej@gmail.com <yermej@gmail.com>:
> >>> On Aug 29, 2:53 pm, dima <dejan.di...@gmail.com> wrote:
> >
> >>> my_new_array = myvalue.inject([]) {|arr, h| arr + h.values}
> >> That's already pretty good (you used #inject ;-)) but this one is
> >> slightly more efficient:
> >>
> >> my_new_array = myvalue.inject([]) {|arr, h| arr.concat h.values}
> >
> > Nice.  You beat me to it.  One of these days, though, I'll read all
> > the Ruby source and exact vengeance upon you guys :)
>
> *gulp*

Hopefully, everybody took that in good stride :)

> To be fair I'd have to say that often intuition errs about what is fast
> and what is wrong in Ruby.  Sometimes algorithms that are supposedly
> faster (for example because a collection is iterated only once vs.
> several times) are actually slower than other variants - at least for
> the size of collections that programs typically deal with.  (In this
> case if's of course better to save all those superfluous intermediate
> arrays. :-))

Yes.  I've noticed a good deal of discussion along these lines in this
group, and it fascinates me (thus the comment about the source code
:).

Also, there are good lessons about software engineering in general on
this list (a group comprised of very smart people that sometimes I
feel as if I do not really belong), like: being careful about
emphasizing efficiency in the design phase, and then grabbing the
program by the proverbial balls later on :)

> Kind regards
>
>         robert

Learning a ton of things every day,

Thanks,

Todd