Class: RVGP::Plot::Gnuplot::ChartBuilder

Inherits:
Object
  • Object
show all
Defined in:
lib/rvgp/plot/gnuplot.rb

Overview

This base class offers some helpers, used by our Element classes to handle common options, and keep things DRY.

Direct Known Subclasses

AreaChart, ColumnAndLineChart

Constant Summary collapse

ONE_MONTH_IN_SECONDS =

30 days

2_592_000

Instance Method Summary collapse

Constructor Details

#initialize(opts, gnuplot) ⇒ ChartBuilder

Create a chart

Parameters:

Options Hash (opts):

  • :domain (Symbol) —

    This option specifies the ‘type’ of the domain. Currently, the only supported type is :monthly

  • :xrange_start (Integer, Date) —

    The plot domain origin, either the number 1, or a date

  • :xrange_end (Date) —

    The end of the plot domain

  • :axis (Hash<Symbol, String>) —

    Axis labels. At the moment, :bottom and :left are supported keys.



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# File 'lib/rvgp/plot/gnuplot.rb', line 91

def initialize(opts, gnuplot)
  # TODO: At some point, we probably want to support inverting the key order.
  #       which, as best I can tell, will involve writing a 'fake' chart,
  #       that's not displayed. But which will create a key, which is
  #       displayed, in the order we want
  @gnuplot = gnuplot

  if opts[:domain]
    @domain = opts[:domain].to_sym
    case @domain
    when :monthly
      # This is mostly needed, because gnuplot doesn't always do the best
      # job of automatically detecting the domain bounds...
      gnuplot.set 'xdata', 'time'
      gnuplot.set 'xtics', ONE_MONTH_IN_SECONDS

      dates = gnuplot.column(0).map { |xtic| Date.strptime xtic, '%m-%y' }.sort
      is_multiyear = dates.first.year != dates.last.year

      unless dates.empty?
        opts[:xrange_start] ||= is_multiyear ? dates.first : Date.new(dates.first.year, 1, 1)
        opts[:xrange_end] ||= is_multiyear ? dates.last : Date.new(dates.last.year, 12, 31)
      end
    else
      raise StandardError, format('Unsupported domain %s', @domain.inspect)
    end
  end

  gnuplot.set 'xrange', format_xrange(opts) if xrange? opts
  gnuplot.set 'xlabel', opts[:axis][:bottom] if opts[:axis] && opts[:axis][:bottom]
  gnuplot.set 'ylabel', opts[:axis][:left] if opts[:axis] && opts[:axis][:left]
end

Instance Method Details

#format_num(num) ⇒ String

Returns the column number specifier, a string, for use by Plot#plot_command, when building charts. In some charts, this is as simple as num + 1. In others, this line can contain more complex gnuplot code.

Returns:

  • (String) —

    Returns the gnuplot formatted series_num, for the series at position num.



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# File 'lib/rvgp/plot/gnuplot.rb', line 135

def format_num(num)
  (num + 1).to_s
end

#series_range(num_cols) ⇒ Enumerator

Returns a enumerator, for use by Plot#plot_command, when building charts. Mostly, this method is what determines if the series are started from one, going up to numcols. Or, are started from num_cols, and go down to one.

Returns:

  • (Enumerator) —

    An enumerator to progress through the chart’s series



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# File 'lib/rvgp/plot/gnuplot.rb', line 128

def series_range(num_cols)
  reverse_series_range? ? (num_cols - 1).downto(1) : 1.upto(num_cols - 1)
end