module NMatrix::IO::Market

Matrix Market is a repository of test data for use in studies of algorithms for numerical linear algebra. There are 3 file formats used:

This module can load and save the first format. We might support Harwell-Boeing in the future.

The MatrixMarket format is documented in:

Public Class Methods

load(filename) → NMatrix click to toggle source

Load a MatrixMarket file. Requires a filename as an argument.

  • Arguments :

    • filename -> String with the filename to be saved.

  • Raises :

    • IOError -> expected type code line beginning with '%%MatrixMarket matrix'

# File lib/nmatrix/io/market.rb, line 65
def load(filename)

  f = File.new(filename, "r")

  header = f.gets
  header.chomp!
  raise(IOError, "expected type code line beginning with '%%MatrixMarket matrix'") if header !~ /^\%\%MatrixMarket\ matrix/

  header = header.split

  entry_type = header[3].downcase.to_sym
  symmetry   = header[4].downcase.to_sym
  converter, default_dtype = CONVERTER_AND_DTYPE[entry_type]

  if header[2] == 'coordinate'
    load_coordinate f, converter, default_dtype, entry_type, symmetry
  else
    load_array f, converter, default_dtype, entry_type, symmetry
  end
end
save(matrix, filename, options = {}) → true click to toggle source

Can optionally set :symmetry to :general, :symmetric, :hermitian; and can set :pattern => true if you're writing a sparse matrix and don't want values stored.

  • Arguments :

    • matrix -> NMatrix with the data to be saved.

    • filename -> String with the filename to be saved.

  • Raises :

    • DataTypeError -> MatrixMarket does not support Ruby objects.

    • ArgumentError -> Expected two-dimensional NMatrix.

# File lib/nmatrix/io/market.rb, line 99
def save(matrix, filename, options = {})
  options = {:pattern => false,
    :symmetry => :general}.merge(options)

  mode = matrix.stype == :dense ? :array : :coordinate
  if [:object].include?(matrix.dtype)
    raise(DataTypeError, "MatrixMarket does not support Ruby objects")
  end
  entry_type = options[:pattern] ? :pattern : ENTRY_TYPE[matrix.dtype]

  raise(ArgumentError, "expected two-dimensional NMatrix") if matrix.dim != 2

  f = File.new(filename, 'w')

  f.puts "%%MatrixMarket matrix #{mode} #{entry_type} #{options[:symmetry]}"

  if matrix.stype == :dense
    save_array matrix, f, options[:symmetry]
  elsif [:list,:yale].include?(matrix.stype)
    save_coordinate matrix, f, options[:symmetry], options[:pattern]
  end

  f.close

  true
end

Protected Class Methods

load_array(file, converter, dtype, entry_type, symmetry) click to toggle source 
# File lib/nmatrix/io/market.rb, line 178
def load_array file, converter, dtype, entry_type, symmetry
  mat = nil

  line = file.gets
  line.chomp!
  line.lstrip!

  fields = line.split

  mat = NMatrix.new :dense, [fields[0].to_i, fields[1].to_i], dtype

  (0...mat.shape[1]).each do |j|
    (0...mat.shape[0]).each do |i|
      datum = file.gets.chomp.send(converter)
      mat[i,j] = datum

      unless i == j || symmetry == :general
        if symmetry == :symmetric
          mat[j,i] = datum
        elsif symmetry == :hermitian
          mat[j,i] = Complex.new(datum.real, -datum.imag)
        elsif symmetry == :'skew-symmetric'
          mat[j,i] = -datum
        end
      end
    end
  end

  file.close

  mat
end
load_coordinate(file, converter, dtype, entry_type, symmetry) click to toggle source

Creates a :list NMatrix from a coordinate-list MatrixMarket file.

# File lib/nmatrix/io/market.rb, line 213
def load_coordinate file, converter, dtype, entry_type, symmetry

  mat = nil

  # Read until we get the dimensions and nonzeros
  while line = file.gets
    line.chomp!
    line.lstrip!
    line, comment = line.split('%', 2) # ignore comments
    if line.size > 4
      shape0, shape1 = line.split
      mat = NMatrix.new(:list, [shape0.to_i, shape1.to_i], 0, dtype)
      break
    end
  end

  # Now read the coordinates
  while line = file.gets
    line.chomp!
    line.lstrip!
    line, comment = line.split('%', 2) # ignore comments

    next unless line.size >= 5 # ignore empty lines

    fields = line.split

    i = fields[0].to_i - 1
    j = fields[1].to_i - 1
    datum = entry_type == :pattern ? 1 : fields[2].send(converter)

    mat[i, j] = datum # add to the matrix
    unless i == j || symmetry == :general
      if symmetry == :symmetric
        mat[j, i] = datum
      elsif symmetry == :'skew-symmetric'
        mat[j, i] = -datum
      elsif symmetry == :hermitian
        mat[j, i] = Complex.new(datum.real, -datum.imag)
      end
    end
  end

  file.close

  mat
end
save_array(matrix, file, symmetry) click to toggle source 
# File lib/nmatrix/io/market.rb, line 157
def save_array matrix, file, symmetry
  file.puts [matrix.shape[0], matrix.shape[1]].join("\t")

  if symmetry == :general
    (0...matrix.shape[1]).each do |j|
      (0...matrix.shape[0]).each do |i|
        file.puts matrix[i,j]
      end
    end
  else # :symmetric, :'skew-symmetric', :hermitian
    (0...matrix.shape[1]).each do |j|
      (j...matrix.shape[0]).each do |i|
        file.puts matrix[i,j]
      end
    end
  end

  file
end
save_coordinate(matrix, file, symmetry, pattern) click to toggle source 
# File lib/nmatrix/io/market.rb, line 129
def save_coordinate matrix, file, symmetry, pattern
  # Convert to a hash in order to store
  rows = matrix.to_h

  # Count non-zeros
  count = 0
  rows.each_pair do |i, columns|
    columns.each_pair do |j, val|
      next if symmetry != :general && j > i
      count += 1
    end
  end

  # Print dimensions and non-zeros
  file.puts "#{matrix.shape[0]}\t#{matrix.shape[1]}\t#{count}"

  # Print coordinates
  rows.each_pair do |i, columns|
    columns.each_pair do |j, val|
      next if symmetry != :general && j > i
      file.puts(pattern ? "\t#{i+1}\t#{j+1}" : "\t#{i+1}\t#{j+1}\t#{val}")
    end
  end

  file
end