From: Robert Klemme <shortcutter@...>
Date: 2007-10-04T20:36:57+09:00
Subject: Re: a newbie question~ about 2 dimension hash? really appreciate~

2007/10/4, Robert Dober <robert.dober@gmail.com>:
> On 10/4/07, vivalon@gmail.com <vivalon@gmail.com> wrote:
> > I want to create a 2 dimension hash, and init it like
> >       A  B  C  D  E
> > A    0  0   0  0   0
> > B    0  0   0  0   0
> > C    0  0   0  0   0
> > D    0  0   0  0   0
> > E    0  0   0  0   0
> >
> > then I can set it by ARGV
> > for example, if ARGV is AB2, BC5, CD7,AE6,CA2, DB3,DE8, EA3, EC9
> > then the expect result is
> >       A  B  C  D  E
> > A    0  2   0  0   6
> > B    0  0   5  0   0
> > C    2  0   0  7   0
> > D    0  3   0  0   8
> > E    3  0   9  0   0
> >
> > well, I wrote some codes like this
> > #############################################
> > ALL="A".."E"
> > dimension={}
> > def init(dime)
> >         tmp={}
> >         ALL.each do |letter|
> >                 tmp[letter]=0
> >         end
> >         ALL.each do |letter|
> >                 dime[letter]=tmp
> >         end
> >         puts "Testing Init"
> >         ALL.each do |key1|
> >                 ALL.each do |key2|
> >                         print key1+key2+" value="
> >                         puts dime[key1][key2]
> >                 end
> >         end
> >         print "Test init is over\n\n"
> > end
> > def test(array,dime)
> >         array.each do |arr|
> >                 dime[arr[0].chr][arr[1].chr]=Integer(arr[2].chr)
> >         end
> >         puts "Testing"
> >         ALL.each do |key1|
> >                 ALL.each do |key2|
> >                         print key1+key2+" value="
> >                         puts dime[key1][key2]
> >                 end
> >                 print "\n"
> >         end
> >         print "Test is over\n\n"
> > end
> >
> > init(dimension)
> > test(ARGV, dimension)
> > #############################################
> > then the result will be
> >
> >       A  B  C  D  E
> > A    3  3   9  7   0
> > B    3  3   9  7   0
> > C    3  3   9  7   0
> > D    3  3   9  7   0
> > E    3  3   9  7   0
> >
> > please tell me why i am wrong?
> > I thought the "last" decide the whole volume
> > like EC9 make C volume 9
> > EA3 make A volume 3
> > please help me~
> > thank you so much~
> >
> >
> >
> Sorry for not having more time right now but the pattern recalls shared objects
> when you do this
>
> c> dime[letter]=tmp
>
> in init you share all lines and they will always refer to the same object.
>
> try this and tell me if that solves your issue
>
> c> dime[letter]=tmp.dup
>
> HTH
> Robert

I guess you are right with regard to the aliasing effect.

Here's another solution:

RKlemme@padrklemme1 /cygdrive/c/SCMws/RKlemme
$ cat ~/ruby/matrix.rb
#!ruby
ALL="A".."E"
args = %w{AB2 BC5 CD7 AE6 CA2 DB3 DE8 EA3 EC9}
matrix = Hash.new 0
args.each do |a|
  d1, d2, v = a.scan /./
  matrix[[d1, d2]] = v.to_i
end

print "  ", ALL.to_a.join(" "), "\n"
ALL.each do |d1|
  print d1
  ALL.each do |d2|
    print " ", matrix[[d1,d2]]
  end
  print "\n"
end

require 'pp'
pp matrix

RKlemme@padrklemme1 /cygdrive/c/SCMws/RKlemme
$ ~/ruby/matrix.rb
  A B C D E
A 0 2 0 0 6
B 0 0 5 0 0
C 2 0 0 7 0
D 0 3 0 0 8
E 3 0 9 0 0
{["A", "E"]=>6,
 ["A", "B"]=>2,
 ["D", "B"]=>3,
 ["C", "A"]=>2,
 ["E", "C"]=>9,
 ["D", "E"]=>8,
 ["C", "D"]=>7,
 ["E", "A"]=>3,
 ["B", "C"]=>5}

Kind regards

robert