Question

I have several hashes

hash1 = { :c1234 => 0.7, :c1237 => 0.8, :c1634 => 0.6, :c1224 => 0.3, :c1291 => 0.1 }
hash2 = { :c1234 => 0.5, :c1136 => 0.2, :c1634 => 0.7, :c1524 => 0.1, :c2291 => 0.9, :c2391 => 0.7 }
hash3 = { :c1234 => 0.3, :c1136 => 0.4, :c6321 => 0.5 }

I need to create matrix from these hashes like

numhash c1234 c1237 c1634 c1224 c1291 c1136 c1524 c2291 c2391 c6321
hash1     0.7   0.8   0.6   0.3   0.1     0     0     0     0     0
hash2     0.5     0   0.7     0     0   0.2   0.1   0.9   0.7     0
hash3     0.3     0     0     0     0   0.4     0     0     0   0.5

numhash = 3 (number of hashes)

Please help me to do it in Ruby.

Answer 1

You should store your hashes not in many local variables, but instead in an enumerable collection, like an Array or Hash. For example, using a hash to name each hash “row”:

data = {
  h1:     {c1234:0.7,c1237:0.8,c1634:0.6,c1224:0.3,c1291:0.1},
  cats:   {c1234:0.5,c1136:0.2,c1634:0.7,c1524:0.1,c2291:0.9,c2391:0.7},
  kittens:{c1234:0.3,c1136:0.4,c6321:0.5}
}

def print_grid(data)
  cols     = data.values.flat_map(&:keys).uniq.sort
  head     = data.keys.map(&:length).max
  template = "%#{head}s | #{cols.map{ |c| "%#{c.length}s" }.join(' | ')}"
  puts template % [ "", *cols ]
  data.each do |row,pairs|
    values = cols.map{ |col| pairs[col] || 0.0 }
    puts template % [ row, *values ]
  end
  puts "", "numhashes: #{data.length}"
end

print_grid(data)    
#=>         | c1136 | c1224 | c1234 | c1237 | c1291 | c1524 | c1634 | c2291 | c2391 | c6321
#=>      h1 |   0.0 |   0.3 |   0.7 |   0.8 |   0.1 |   0.0 |   0.6 |   0.0 |   0.0 |   0.0
#=>    cats |   0.2 |   0.0 |   0.5 |   0.0 |   0.0 |   0.1 |   0.7 |   0.9 |   0.7 |   0.0
#=> kittens |   0.4 |   0.0 |   0.3 |   0.0 |   0.0 |   0.0 |   0.0 |   0.0 |   0.0 |   0.5
#=> 
#=> numhashes: 3

If you change the last map to…

values = columns.map{ |col| pairs[col] || "-" }

then you get:

        | c1136 | c1224 | c1234 | c1237 | c1291 | c1524 | c1634 | c2291 | c2391 | c6321
     h1 |     - |   0.3 |   0.7 |   0.8 |   0.1 |     - |   0.6 |     - |     - |     -
   cats |   0.2 |     - |   0.5 |     - |     - |   0.1 |   0.7 |   0.9 |   0.7 |     -
kittens |   0.4 |     - |   0.3 |     - |     - |     - |     - |     - |     - |   0.5