From: "shortcutter@..." <shortcutter@...>
Date: 2008-05-28T23:05:32+09:00
Subject: Re: Merge collections of objects

On 28 Mai, 15:42, Alex Fenton <af...@deleteme.cam.ac.uk> wrote:
> John Butler wrote:
> > Hi,
>
> > I wonder if there is a quick way to do this.
>
> > companyA has 2 employees "a", "b"
>
> > companyB has 3 employees "a", "b", "c"
>
> > I basically want to merge companyA employess with companyB employees so
> > when i look at companyA the employees will equal "a", "b", "c"
>
> Try the "|" method of Array
>
> irb(main):001:0> comp_a = %w[a b c]
> => ["a", "b", "c"]
> irb(main):002:0> comp_b = %w[a b]
> => ["a", "b"]
> irb(main):003:0> comp_a | comp_b
> => ["a", "b", "c"]
> irb(main):004:0> comp_a & comp_b
> => ["a", "b"]
>
> a

For efficient processing of large collections there's also Set and
Hash.

irb(main):001:0> a=%w{a b c}
=> ["a", "b", "c"]
irb(main):002:0> b=%w{b c d}
=> ["b", "c", "d"]
irb(main):003:0> a.to_set | b.to_set
=> #<Set: {"a", "b", "c", "d"}>

irb(main):004:0> h=Hash.new 0
=> {}
irb(main):005:0> [a,b].each {|c| c.each {|x| h[x]+=1}}
=> [["a", "b", "c"], ["b", "c", "d"]]
irb(main):006:0> h.keys
=> ["a", "b", "c", "d"]
irb(main):007:0>

etc.

Kind regards

robert