class SVG::Graph::Line

Create presentation quality SVG line graphs easily

Synopsis

require 'SVG/Graph/Line'

fields = %w(Jan Feb Mar);
data_sales_02 = [12, 45, 21]
data_sales_03 = [15, 30, 40]

graph = SVG::Graph::Line.new({
        :height => 500,
        :width => 300,
  :fields => fields,
})

graph.add_data({
        :data => data_sales_02,
  :title => 'Sales 2002',
})

graph.add_data({
        :data => data_sales_03,
  :title => 'Sales 2003',
})

print "Content-type: image/svg+xml\r\n\r\n";
print graph.burn();

Description

This object aims to allow you to easily create high quality SVG line graphs. You can either use the default style sheet or supply your own. Either way there are many options which can be configured to give you control over how the graph is generated - with or without a key, data elements at each point, title, subtitle etc.

Examples

www.germane-software/repositories/public/SVG/test/single.rb

Notes

Only number of fileds datapoints will be drawn, additional data values are ignored. Nil values in data are skipped and interpolated as straight line to the next datapoint.

The default stylesheet handles upto 10 data sets, if you use more you must create your own stylesheet and add the additional settings for the extra data sets. You will know if you go over 10 data sets as they will have no style and be in black.

See also

Author

Sean E. Russell <serATgermaneHYPHENsoftwareDOTcom>

Copyright 2004 Sean E. Russell This software is available under the Ruby license

Attributes

area_fill[RW]

Fill in the area under the plot if true

show_data_points[RW]

Show a small circle on the graph where the line goes from one point to the next.

stacked[RW]
Accumulates each data set. (i.e. Each point increased by sum of

all previous series at same point). Default is 0, set to '1' to show.

Public Class Methods

new(config) click to toggle source

The constructor takes a hash reference, :fields (the names for each field on the X axis) MUST be set, all other values are defaulted to those shown above - with the exception of style_sheet which defaults to using the internal style sheet.

Calls superclass method SVG::Graph::Graph::new
# File lib/SVG/Graph/Line.rb, line 88
def initialize config
    raise "fields was not supplied or is empty" unless config[:fields] &&
    config[:fields].kind_of?(Array) &&
    config[:fields].length > 0
    super
end

Public Instance Methods

set_defaults() click to toggle source

In addition to the defaults set in Graph::initialize, sets

show_data_points

true

show_data_values

true

stacked

false

area_fill

false

# File lib/SVG/Graph/Line.rb, line 100
def set_defaults
  init_with(
    :show_data_points   => true,
    :show_data_values   => true,
    :stacked            => false,
    :area_fill          => false
  )
end

Protected Instance Methods

calc_coords(field, value, width = field_width, height = field_height) click to toggle source
# File lib/SVG/Graph/Line.rb, line 183
def calc_coords(field, value, width = field_width, height = field_height)
  coords = {:x => 0, :y => 0}
  coords[:x] = width * field
  # make sure we do float division, otherwise coords get messed up
  coords[:y] = @graph_height - (value + @y_offset)/@y_scale_division.to_f * height
  return coords
end
calculate_left_margin() click to toggle source
Calls superclass method SVG::Graph::Graph#calculate_left_margin
# File lib/SVG/Graph/Line.rb, line 150
def calculate_left_margin
  super
  label_left = @config[:fields][0].length / 2 * font_size * 0.6
  @border_left = label_left if label_left > @border_left
end
draw_data() click to toggle source
# File lib/SVG/Graph/Line.rb, line 191
def draw_data
  minvalue = min_value
  fieldheight = field_height
  fieldwidth = field_width
  line = @data.length
  # always zero for filling areas
  prev_sum = Array.new(@config[:fields].length).fill(-@y_offset)
  # cumulated sum (used for stacked graphs)
  cum_sum = Array.new(@config[:fields].length).fill(nil)

  for data in @data.reverse
    lpath = ""
    apath = ""

    # reset cum_sum if we are not in a stacked graph
    if not stacked then cum_sum.fill(nil) end

    # only consider as many datapoints as we have fields
    @config[:fields].each_index do |i|
      next if data[:data][i].nil?
      if cum_sum[i].nil? #first time init
        cum_sum[i] = data[:data][i] - minvalue
      else # in case of stacked
        cum_sum[i] += data[:data][i]
      end
      c = calc_coords(i, cum_sum[i], fieldwidth, fieldheight)
      lpath << "#{c[:x]} #{c[:y]} "
    end

    if area_fill
      if stacked then
        (prev_sum.length - 1).downto 0 do |i|
          next if prev_sum[i].nil?
          c = calc_coords(i, prev_sum[i], fieldwidth, fieldheight)

          apath << "#{c[:x]} #{c[:y]} "
        end

        c = calc_coords(0, prev_sum[0], fieldwidth, fieldheight)
      else
        apath = "V#@graph_height"
        c = calc_coords(0, -@y_offset, fieldwidth, fieldheight)
      end

      @graph.add_element("path", {
        "d" => "M#{c[:x]} #{c[:y]} L" + lpath + apath + "Z",
        "class" => "fill#{line}"
      })
    end

    @graph.add_element("path", {
      "d" => "M0 #@graph_height L" + lpath,
      "class" => "line#{line}"
    })

    if show_data_points || show_data_values || add_popups
      cum_sum.each_index do |i|
        # skip datapoint if nil
        next if cum_sum[i].nil?
        c = calc_coords(i, cum_sum[i], fieldwidth, fieldheight)
        if show_data_points
          shape_selection_string = data[:description][i].to_s
          if !data[:shape][i].nil?
            shape_selection_string = data[:shape][i].to_s
          end
          DataPoint.new(c[:x], c[:y], line).shape(shape_selection_string).each{|s|
            @graph.add_element( *s )
          }
        end

        make_datapoint_text( c[:x], c[:y] - font_size/2, cum_sum[i] + minvalue)
        # number format shall not apply to popup (use .to_s conversion)
        descr = ""
        if !data[:description][i].to_s.empty?
          descr = ", #{data[:description][i].to_s}"
        end
        add_popup(c[:x], c[:y], (cum_sum[i] + minvalue).to_s + descr, "", data[:url][i].to_s)
      end
    end

    prev_sum = cum_sum.dup
    line -= 1
  end
end
get_css() click to toggle source
# File lib/SVG/Graph/Line.rb, line 277
      def get_css
        return <<EOL
/* default line styles */
.line1{
        fill: none;
        stroke: #ff0000;
        stroke-width: 1px;
}
.line2{
        fill: none;
        stroke: #0000ff;
        stroke-width: 1px;
}
.line3{
        fill: none;
        stroke: #00ff00;
        stroke-width: 1px;
}
.line4{
        fill: none;
        stroke: #ffcc00;
        stroke-width: 1px;
}
.line5{
        fill: none;
        stroke: #00ccff;
        stroke-width: 1px;
}
.line6{
        fill: none;
        stroke: #ff00ff;
        stroke-width: 1px;
}
.line7{
        fill: none;
        stroke: #00ffff;
        stroke-width: 1px;
}
.line8{
        fill: none;
        stroke: #ffff00;
        stroke-width: 1px;
}
.line9{
        fill: none;
        stroke: #ccc6666;
        stroke-width: 1px;
}
.line10{
        fill: none;
        stroke: #663399;
        stroke-width: 1px;
}
.line11{
        fill: none;
        stroke: #339900;
        stroke-width: 1px;
}
.line12{
        fill: none;
        stroke: #9966FF;
        stroke-width: 1px;
}
/* default fill styles */
.fill1{
        fill: #cc0000;
        fill-opacity: 0.2;
        stroke: none;
}
.fill2{
        fill: #0000cc;
        fill-opacity: 0.2;
        stroke: none;
}
.fill3{
        fill: #00cc00;
        fill-opacity: 0.2;
        stroke: none;
}
.fill4{
        fill: #ffcc00;
        fill-opacity: 0.2;
        stroke: none;
}
.fill5{
        fill: #00ccff;
        fill-opacity: 0.2;
        stroke: none;
}
.fill6{
        fill: #ff00ff;
        fill-opacity: 0.2;
        stroke: none;
}
.fill7{
        fill: #00ffff;
        fill-opacity: 0.2;
        stroke: none;
}
.fill8{
        fill: #ffff00;
        fill-opacity: 0.2;
        stroke: none;
}
.fill9{
        fill: #cc6666;
        fill-opacity: 0.2;
        stroke: none;
}
.fill10{
        fill: #663399;
        fill-opacity: 0.2;
        stroke: none;
}
.fill11{
        fill: #339900;
        fill-opacity: 0.2;
        stroke: none;
}
.fill12{
        fill: #9966FF;
        fill-opacity: 0.2;
        stroke: none;
}
/* default line styles */
.key1,.dataPoint1{
        fill: #ff0000;
        stroke: none;
        stroke-width: 1px;
}
.key2,.dataPoint2{
        fill: #0000ff;
        stroke: none;
        stroke-width: 1px;
}
.key3,.dataPoint3{
        fill: #00ff00;
        stroke: none;
        stroke-width: 1px;
}
.key4,.dataPoint4{
        fill: #ffcc00;
        stroke: none;
        stroke-width: 1px;
}
.key5,.dataPoint5{
        fill: #00ccff;
        stroke: none;
        stroke-width: 1px;
}
.key6,.dataPoint6{
        fill: #ff00ff;
        stroke: none;
        stroke-width: 1px;
}
.key7,.dataPoint7{
        fill: #00ffff;
        stroke: none;
        stroke-width: 1px;
}
.key8,.dataPoint8{
        fill: #ffff00;
        stroke: none;
        stroke-width: 1px;
}
.key9,.dataPoint9{
        fill: #cc6666;
        stroke: none;
        stroke-width: 1px;
}
.key10,.dataPoint10{
        fill: #663399;
        stroke: none;
        stroke-width: 1px;
}
.key11,.dataPoint11{
        fill: #339900;
        stroke: none;
        stroke-width: 1px;
}
.key12,.dataPoint12{
        fill: #9966FF;
        stroke: none;
        stroke-width: 1px;
}
EOL
      end
get_x_labels() click to toggle source
# File lib/SVG/Graph/Line.rb, line 146
def get_x_labels
  @config[:fields]
end
get_y_labels() click to toggle source
# File lib/SVG/Graph/Line.rb, line 156
def get_y_labels
  maxvalue = max_value
  minvalue = min_value
  range = maxvalue - minvalue
  # add some padding on top of the graph
  if range == 0
    maxvalue += 10
  else
    maxvalue += range / 20.0
  end
  scale_range = maxvalue - minvalue

  @y_scale_division = scale_divisions || (scale_range / 10.0)
  @y_offset = 0

  if scale_integers
    @y_scale_division = @y_scale_division < 1 ? 1 : @y_scale_division.round
    @y_offset = (minvalue.to_f - minvalue.floor).to_f
    minvalue = minvalue.floor
  end

  rv = []

  minvalue.step( maxvalue, @y_scale_division ) {|v| rv << v}
  return rv
end
max_value() click to toggle source
# File lib/SVG/Graph/Line.rb, line 111
def max_value
  max = 0
  if stacked
    sums = Array.new(@config[:fields].length).fill(0)

    @data.each do |data|
      sums.each_index do |i|
        sums[i] += data[:data][i].to_f
      end
    end
    max = sums.max
  else
    # compact removes nil values when computing the max
    max = @data.collect{ |x|
      x[:data].compact.max
    }.max
  end

  return max
end
min_value() click to toggle source
# File lib/SVG/Graph/Line.rb, line 132
def min_value
  min = 0
  # compact removes nil values
  if (!min_scale_value.nil?) then
    min = min_scale_value
  elsif (stacked == true) then
    min = @data[-1][:data].compact.min
  else
    min = @data.collect{|x| x[:data].compact.min}.min
  end

  return min
end