custom_file_format.rb

# Create a new file format class based on the built-in Rails format.
# The name of the class should reflect the filename, i.e.: filename.camelize.

class CustomFileFormat < RequestLogAnalyzer::FileFormat::Rails
  
  # Regular expressions galore!
  line_definition :current_user do |line|
    line.regexp = /Logged in as ([^ ]+) \((\w+)\)/
    line.capture(:email).as(:string)
    line.capture(:account_type).as(:string)
  end
  
  line_definition :current_locale do |line|
    line.regexp = /Using locale "([^"]+)"/
    line.capture(:locale).as(:string)
  end
  
  # Append something to the report
  report(:append) do |analyze|
    analyze.frequency :account_type, :title => "Account type"
    analyze.frequency :locale, :title => "Locales"
  end
end

Shell invocation

~ $ request-log-analyzer production.log   # Analyze production.log
      --format custom_file_format.rb      # Use custom file format
      --reject account_type free          # Ignore requests from free accounts
      --select locale en-US               # Only look at en-US locale requests
      --output HTML --file report.html    # Generate an HTML report as report.html