Решено How can I capture STDOUT to a string? to a file?

def with_captured_stdout
  original_stdout = $stdout
  $stdout = StringIO.new
  yield
  $stdout.string
ensure
  $stdout = original_stdout
end

require 'csv'
require 'ruby-fann'

require 'tempfile'

# https://stackoverflow.com/questions/4459330/how-do-i-temporarily-redirect-stderr-in-ruby/4459463#4459463
# require "stringio"
# def capture_stderr
#   # The output stream must be an IO-like object. In this case we capture it in
#   # an in-memory IO object so we can return the string value. You can assign any
#   # IO object here.
#   previous_stderr, $stderr = $stderr, StringIO.new
#   yield
#   $stderr.string
# ensure
#   # Restore the previous value of stderr (typically equal to STDERR).
#   $stderr = previous_stderr
# end

def capture_stdout(&block)
  stdout_orig = $stdout
  stdout_mock = StringIO.new
  $stdout = stdout_mock

  begin
    result = block.call
  ensure
    $stdout = stdout_orig
  end

  [result, stdout_mock.string]
end


# Recompilation of https://stackoverflow.com/questions/4459330/how-do-i-temporarily-redirect-stderr-in-ruby/4459463#4459463 (which can't be used because of natve extension writes)
# and https://stackoverflow.com/questions/9026977/how-to-silence-printf-called-from-within-a-ruby-c-extension/9073643#9073643
# @TODO use temporary file (https://ruby-doc.org/stdlib-2.4.0/libdoc/tempfile/rdoc/Tempfile.html) and re-read it at end
def silence_stdout(log = '/dev/null')
  orig = $stdout.dup
  $stdout.reopen(File.new(log, 'w'))
  begin
    yield
  ensure
    $stdout = orig
  end
end

x_data = []
y_data = []
# Load data from CSV file into two arrays - one for independent variables X and one for the dependent variable Y
CSV.foreach("./data/admission.csv", :headers => false) do |row|
  x_data.push( [row[0].to_f, row[1].to_f] )
  #x_data.push( [row[0].to_f, row[1].to_f] )
  y_data.push( [row[2].to_i] )
end

# Divide data into a training set and test set
test_size_percentange = 20.0 # 20.0%
test_set_size = x_data.size * (test_size_percentange/100.to_f)

test_x_data = x_data[0 .. (test_set_size-1)]
test_y_data = y_data[0 .. (test_set_size-1)]

training_x_data = x_data[test_set_size .. x_data.size]
training_y_data = y_data[test_set_size .. y_data.size]

# Setup training data model
train = RubyFann::TrainData.new( :inputs=> training_x_data, :desired_outputs=>training_y_data )

# Setup model and train using training data
model = RubyFann::Standard.new(
              num_inputs: 2,
              hidden_neurons: [6],
              num_outputs: 1 )

silence_stdout('ttt.log') do
  # 5000 max_epochs, 100 errors between reports and 0.01 desired mean-squared-error
  model.train_on_data(train, 5000, 500, 0.01)
end

# Predict single class
prediction = model.run( [45, 85] )
# Round the output to get the prediction
puts "Algorithm predicted class: #{prediction.map{ |e| e.round }}"

predicted = []
test_x_data.each do |params|
  predicted.push( model.run(params).map{ |e| e.round } )
end

correct = predicted.collect.with_index { |e,i| (e == test_y_data[i]) ? 1 : 0 }.inject{ |sum,e| sum+e }

puts "Accuracy: #{((correct.to_f / test_set_size) * 100).round(2)}% - test set of size #{test_size_percentange}%"