simple ruby console histogram generator

puts_hist.rb

# Pass in an enumeration of data and
# (optionally) a block to extract the grouping aspect of the data.
#
# Optional: sort_by lambda (operates on group key and count)

def puts_hist(data, sort_by: nil, &block)
  data = data.map(&block) if block
  counts = data.each_with_object(Hash.new(0)) { |k, h| h[k] += 1 }
  max = counts.values.max
  width = ENV['COLUMNS'].to_i
  width0 = counts.keys.map { |k| k.to_s.length }.max
  width1 = width - width0 - 3
  div = [1, max / width1.to_f].max
  puts "max: %d; widths: %d, %d; divisor: %0.3f" % [max, width0, width1, div]
  counts = counts.sort_by(&sort_by) if sort_by
  counts.each do |k, c|
    puts "%#{width0}s: %-#{width1}s" % [k, "\u283F" * ((c / div).round)]
  end
  counts
end