Useful script for quickly pulling data out of csv's into a ruby console.

csv_parser.rb

require 'csv'
require 'pry'
require 'active_support/all'

class CSVParser
  attr_accessor :filename, :items, :rows, :options, :headers

  # Optional params:
  # -nh No header in csv
  def initialize(args)
    @options = build_options(args)
    @filename = build_filename(args)
    @headers = []
    @items = options[:no_header] ? [] : HashWithIndifferentAccess.new
    @rows = []
    load_csv
  end

  def method_missing(method_name)
    if items[method_name].present?
      print_array_for_console items[method_name]
    else
      puts "No items found for #{method_name}"
    end
  end

  def perform
    if headers.present?
      puts "Headers:"
      headers.each{|header| puts header}
    else
      puts "No headers"
    end

    console
  end

  def console
    binding.pry
  end

  def load_csv(can_retry=true)
    begin
      if options[:no_header]
        @headers = nil
        CSV.foreach(filename, csv_header_options) do |row|
          row.count.times{|i| items[i] = []}
          break
        end
      else
        # Grab header info and initialize array
        CSV.foreach(filename, csv_header_options) do |row|
          @headers = row.headers
          @headers.each{ |header| items[header] = []}
          break
        end
      end
      # Grab each row and collect items
      CSV.foreach(filename, csv_header_options) do |row|
        if headers.nil?
          row.each_with_index{|data, i| items[i] << data}
        else
          @headers.each{ |header| items[header] << row[header] }
        end
        rows << row.map{|k, v| v}
      end
    rescue => e
      puts e.message + " ... retrying with new encoding..."
      @csv_options[:encoding] = 'ISO-8859-1'
      load_csv(false) if can_retry
    end
  end

#Change a fixnum to a string with proper commas
  def commas(number)
    number = number.to_s
    chunks = []
    number.reverse!
    while (number.length > 0)
      chunks << number.slice!(0,3)
    end
    number = chunks.join(',')
    number.reverse!
  end


  # Builds a hash of the parsed data, indexed at index
  # @param [Symbol] index Index of hash
  def build_hash(index)
    raise unless headers.include?(index)
    hash = {}
    rows.each do |row|
      hash[row[index]] = {}
      row.each do |k, v|
        next if k == index
        hash[row[index]][k] = v
      end
    end
    hash
  end

  # Print array to console in a ruby copypasta way e.g. [item1, item2, item3]
  # items should be an array
  def print_array_for_console(items, format = nil)
    print "["
    i = 0
    count = items.count
    while i < (count - 1)
      print_item(items[i], format)
      print ", "
      i += 1
    end
    print_item(items.last, format)
    print "]"
  end

  private

  def build_filename(args)
    filepaths.each do |filepath|
      file_name = filepath
      file_name += args.count > 1 ? args.join(" ") : args[0]
      file_name += ".csv" unless file_name.include?(".csv")

      if Dir[file_name].empty?
        file_list = Dir[filepath + "*"].select{|x| x.include? args[0]}
        if file_list.count == 1
          file_name = file_list.first
        elsif file_list.count == 0
          next
        else
          puts "Filename ambiguous, choose from list:"
          file_list.each_with_index do |file, i|
            puts "#{i + 1}) #{file}"
          end
          answer = STDIN.gets.chomp
          file_name = file_list[answer.to_i - 1]
        end
      end
      return file_name
    end
    raise StandardError, "File not found"
  end

  def build_options(args)
    options = {}
    args.each do |arg|
      if available_options.keys.include?(arg)
        options[available_options[arg]] = true
        args.delete(arg)
      end
    end
    options
  end

  def filepaths
    ["/Users/andrewkotka/Downloads/",
     "/Users/andrewkotka/Desktop/"]
  end

  def csv_header_options
    @csv_options ||= options[:no_header] ? {} : {:headers => true, :header_converters => :symbol}
  end

  def available_options
    {"-nh" => :no_header}
  end

  # Prints item to console based on format
  def print_item(item, format)
    case format
    when :quotes
      print "\"" + item + "\""
    when :no_quotes
      print item
    else
      print smart_quotes(item)
    end
  end

  # Guess about whether or not to print quotes
  def smart_quotes(item)
    # No quotes if number
    return item if item.class == Fixnum
    # No quotes if probably a number in string form
    return item if item.to_i.to_s.length == item.length
    return "\"" + item + "\""
  end
end

parser = CSVParser.new(ARGV)
parser.perform

I have 2 aliases set up as follows:
alias cpro="cd ~/Desktop/custom\ programs/"
alias parse="cpro && ruby ~/Desktop/custom\ programs/csv_parser.rb"

Then I can just type "parse csvname.csv" in the console. Script will handle names with or without spaces and names with or without .csv.

The script will open up a console with the csv parsed in as both whole rows and aggregated columns. Methods available for friendly copypasta from console and printing comma delimited numbers.

Updated to take in params for no header (-nh) and added method to build hash based off an index (e.g. user_email).

TODO: add permanent config, add -p arg for path.