How do I temporarily redirect stderr in Ruby on Rails?

Hi, gays. I would like to ask for advice.
I asked this question on StackOverflow , but I did not receive an answer.
Help please.

I can't get this code to work on rails! But in ruby it works.
You can try:

require 'csv'
require 'ruby-fann'

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, 55] )
# 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}%"

Tell me please how to get this output to a file? or to a string? -

Max epochs     5000. Desired error: 0.0099999998.
Epochs            1. Current error: 0.2511504292. Bit fail 80.
Epochs          500. Current error: 0.0143846525. Bit fail 3.
Epochs         1000. Current error: 0.0127008855. Bit fail 3.
Epochs         1500. Current error: 0.0125084650. Bit fail 3.
Epochs         2000. Current error: 0.0118288267. Bit fail 3.
Epochs         2500. Current error: 0.0111219604. Bit fail 2.
Epochs         3000. Current error: 0.0118827689. Bit fail 3.
Epochs         3500. Current error: 0.0118078245. Bit fail 2.
Epochs         4000. Current error: 0.0112144882. Bit fail 1.
Epochs         4500. Current error: 0.0117674908. Bit fail 2.
Epochs         5000. Current error: 0.0127671538. Bit fail 4.

I made a demo, but I can not show the console output at the finish.
Any ideas? Thank you.

P.S. admission.csv

What do you expect the output to be? A web page? If yes, you need to:

• Put all of this code into a controller, and instead of 'puts', assign the results to an array that contains all the data you want to output.
• Create a view that displays the content of your array.

Ivan Raszl, you did not understand. Read my question on SO:
https://stackoverflow.com/questions/56828359/how-do-i-temporarily-redirect-stderr-in-ruby-on-rails