I did like to convert some programs I wrote in Perl to Ruby. I'm working with sparse three dimensional data. Here's an example in Perl. The array @a has just two elements. The rest are undefined.
#!/usr/bin/perl -w
$a[0][0][0] = 0;
$a[100][100][100] = 100;
print "$a[0][0][0]\n";
print "$a[100][100][100]\n";
The output:
0
100
Is there an easy way to implement this sort of data structure in Ruby? The Array class seems limited to one dimension. I looked at the Matrix class, but there doesn't appear to be any way of assigning values to the individual matrix elements (which seems pretty strange, so maybe I'm overlooking the obvious).
-Bill
···
--
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It's pretty easy if you know the dimensions before hand, a bit more
hackery pokery if you don't.
a = Array.new(101) { Array.new(101) { Array.new(101) } }
a[0][0][0] = 0
a[100][100][100] = 100
puts a[0][0][0]
puts a[100][100][100]
···
On Tue, Oct 03, 2006 at 10:58:22PM +0900, Bill Birkett wrote:
I did like to convert some programs I wrote in Perl to Ruby. I'm
working with sparse three dimensional data. Here's an example in
Perl. The array @a has just two elements. The rest are undefined.
#!/usr/bin/perl -w
$a[0][0][0] = 0;
$a[100][100][100] = 100;
print "$a[0][0][0]\n";
print "$a[100][100][100]\n";
The output:
0
100
Is there an easy way to implement this sort of data structure in
Ruby? The Array class seems limited to one dimension. I looked at the
Matrix class, but there doesn't appear to be any way of assigning
values to the individual matrix elements (which seems pretty strange,
so maybe I'm overlooking the obvious).
Bill Birkett wrote:
I did like to convert some programs I wrote in Perl to Ruby. I'm
working with sparse three dimensional data. Here's an example in
Perl. The array @a has just two elements. The rest are undefined.
#!/usr/bin/perl -w
$a[0][0][0] = 0;
$a[100][100][100] = 100;
print "$a[0][0][0]\n";
print "$a[100][100][100]\n";
The output:
0
100
Is there an easy way to implement this sort of data structure in
Ruby? The Array class seems limited to one dimension. I looked at the
Matrix class, but there doesn't appear to be any way of assigning
values to the individual matrix elements (which seems pretty strange,
so maybe I'm overlooking the obvious).
The solution depends on what you are trying to accomplish. If your aim is to
minimize storage space, then use a nested hash, with numeric indices as
keys. If your aim is simply to create an n-dimensional array and you don't
care about storage size, then follow the advice of another poster:
#!/usr/bin/ruby -w
dim_size = 100
arr = Array.new(dim_size) { Array.new(dim_size) { Array.new(dim_size,42) } }
puts arr[39][56][24]
42
···
--
Paul Lutus
http://www.arachnoid.com
$a[0][0][0] = 0;
$a[100][100][100] = 100;
print "$a[0][0][0]\n";
print "$a[100][100][100]\n";
The output:
0
100
I saw this on inquirylabs.com recently [1]
hsh = Hash.new(&(p=lambda{|h,k| h[k] = Hash.new(&p)}))
hsh[0][0][0] = 0 >> 0
hsh[100][100][100] = 100 >> 100
HTH
Nathan
[1]
http://blog.inquirylabs.com/2006/09/20/ruby-hashes-of-arbitrary-depth/
···
--
Posted via http://www.ruby-forum.com/\.
Close:
a={}
a[[0,0,0]], a[[100,100,100]] = 0, 100
puts "#{a[[0,0,0]]}"
puts "#{a[[100,100,100]]}"
But you might like this better (my Ruby isn't very good, so please excuse me if I overcomplicate these definitions):
class SparseMatrix < Hash
alias :oldget :
alias :oldset :=
def(*i); self.oldget(i); end
def=(*i); v=i.pop; self.oldset(i,v); end
end
a = SparseMatrix.new
a[0,0,0], a[100,100,100] = 0, 100
irb(main):017:0> a
=> {[0, 0, 0]=>0, [100, 100, 100]=>100}
irb(main):018:0> puts "#{a[0,0,0]}"
0
=> nil
irb(main):019:0> puts "#{a[100,100,100]}"
100
=> nil
irb(main):020:0> puts "#{a[2,2,2]}"
=> nil
irb(main):021:0>
-j
Bill Birkett wrote:
···
I did like to convert some programs I wrote in Perl to Ruby. I'm working with sparse three dimensional data. Here's an example in Perl. The array @a has just two elements. The rest are undefined.
#!/usr/bin/perl -w
$a[0][0][0] = 0;
$a[100][100][100] = 100;
print "$a[0][0][0]\n";
print "$a[100][100][100]\n";
The output:
0
100
Is there an easy way to implement this sort of data structure in Ruby? The Array class seems limited to one dimension. I looked at the Matrix class, but there doesn't appear to be any way of assigning values to the individual matrix elements (which seems pretty strange, so maybe I'm overlooking the obvious).
-Bill
irb(main):005:0> hsh[1]
=> {}
irb(main):006:0> hsh[2]
=> {}
irb(main):007:0> hsh[3]
=> {}
irb(main):008:0> hsh
=> {1=>{}, 2=>{}, 3=>{}}
ugh.
-j
Nathan Grant wrote:
···
$a[0][0][0] = 0;
$a[100][100][100] = 100;
print "$a[0][0][0]\n";
print "$a[100][100][100]\n";
The output:
0
100
I saw this on inquirylabs.com recently [1]
hsh = Hash.new(&(p=lambda{|h,k| h[k] = Hash.new(&p)}))
hsh[0][0][0] = 0 >> 0
hsh[100][100][100] = 100 >> 100
HTH
Nathan
[1] http://blog.inquirylabs.com/2006/09/20/ruby-hashes-of-arbitrary-depth/