Method: Aggregate#to_s

Defined in:
lib/aggregate.rb

#to_s(columns = nil) ⇒ Object

Generate a pretty-printed ASCII representation of the histogram



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# File 'lib/aggregate.rb', line 107

def to_s(columns=nil)

  #default to an 80 column terminal, don't support < 80 for now
  if nil == columns
    columns = 80
  else
    raise ArgumentError if columns < 80
  end

  #Find the largest bucket and create an array of the rows we intend to print
  disp_buckets = Array.new
  max_count = 0
  total = 0
  @buckets.each_with_index do |count, idx|
    next if 0 == count
    max_count = [max_count, count].max
    disp_buckets << [idx, to_bucket(idx), count]
    total += count
  end

  #XXX: Better to print just header --> footer
  return "Empty histogram" if 0 == disp_buckets.length

  #Figure out how wide the value and count columns need to be based on their
  #largest respective numbers
  value_str = "value"
  count_str = "count"
  total_str = "Total"
  value_width = [disp_buckets.last[1].to_s.length, value_str.length].max
  value_width = [value_width, total_str.length].max
  count_width = [total.to_s.length, count_str.length].max
  max_bar_width  = columns - (value_width + " |".length + "| ".length + count_width)

  #Determine the value of a '@'
  weight = [max_count.to_f/max_bar_width.to_f, 1.0].max

  #format the header
  histogram = sprintf("%#{value_width}s |", value_str)
  max_bar_width.times { histogram << "-"}
  histogram << sprintf("| %#{count_width}s\n", count_str)

  # We denote empty buckets with a '~'
  def skip_row(value_width)
    sprintf("%#{value_width}s ~\n", " ")
  end

  #Loop through each bucket to be displayed and output the correct number
  prev_index = disp_buckets[0][0] - 1

  disp_buckets.each do |x|
    #Denote skipped empty buckets with a ~
    histogram << skip_row(value_width) unless prev_index == x[0] - 1
    prev_index = x[0]

    #Add the value
    row = sprintf("%#{value_width}d |", x[1])

    #Add the bar
    bar_size = (x[2]/weight).to_i
    bar_size.times { row += "@"}
    (max_bar_width - bar_size).times { row += " " }

    #Add the count
    row << sprintf("| %#{count_width}d\n", x[2])

    #Append the finished row onto the histogram
    histogram << row
  end

  #End the table
  histogram << skip_row(value_width) if disp_buckets.last[0] != bucket_count-1
  histogram << sprintf("%#{value_width}s", "Total")
  histogram << " |"
  max_bar_width.times {histogram << "-"}
  histogram << "| "
  histogram << sprintf("%#{count_width}d\n", total)
end