Here is a helpful script for loading a csv file into an array so you can test regex.

regex-tester.rb

#! /usr/bin/env ruby

require 'csv'

# step 1: import sproducts into an array 
@file = "<your path and file>"  

@sproducts = []
CSV.foreach(@file, :headers => false) do |row|
    @sproducts << row[0]
end

# create variable with regex function I want to test and print the matches
@sproducts.each { |line|
  @matches = /^A.*/.match(line)
  if @matches.nil?
  else  
    puts @matches.to_s 
  end
  }