Class: RailsDataExplorer::Chart::BoxPlot

Inherits:
RailsDataExplorer::Chart show all
Defined in:
lib/rails_data_explorer/chart/box_plot.rb

Overview

Responsibilities:

* Render a box plot for univariate analysis of a quantitative data series.

Collaborators:

* DataSet

Resources:

Instance Attribute Summary

Attributes inherited from RailsDataExplorer::Chart

#output_buffer

Instance Method Summary collapse

Methods inherited from RailsDataExplorer::Chart

#dom_id, #render?

Constructor Details

#initialize(_data_set, options = {}) ⇒ BoxPlot

Returns a new instance of BoxPlot.



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# File 'lib/rails_data_explorer/chart/box_plot.rb', line 17

def initialize(_data_set, options = {})
  @data_set = _data_set
  @options = {}.merge(options)
end

Instance Method Details

#compute_chart_attrs ⇒ Object 



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# File 'lib/rails_data_explorer/chart/box_plot.rb', line 22

def compute_chart_attrs
  x_ds = @data_set.data_series.first
  return false  if x_ds.nil?

  {
    values: [x_ds.values],
    min: x_ds.min_val,
    max: x_ds.max_val,
    base_width: 120,
    base_height: 960,
    axis_tick_format: x_ds.axis_tick_format,
  }
end

#render ⇒ Object 



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# File 'lib/rails_data_explorer/chart/box_plot.rb', line 36

def render
  return ''  unless render?
  ca = compute_chart_attrs
  return ''  unless ca

  %(
    <div id="#{ dom_id }" class="rde-chart rde-box-plot">
      <svg class="box" style="height: #{ ca[:base_width] }px; width: 100%;"></svg>

      <script type="text/javascript">
        (function() {
          var base_width = #{ ca[:base_width] },
              base_height = #{ ca[:base_height] },
              margin = { top: 10, right: 50, bottom: 95, left: 50 },
              width = base_width - margin.left - margin.right,
              height = base_height - margin.top - margin.bottom;

          var min = #{ ca[:min] },
              max = #{ ca[:max] };

          var chart = d3.box()
                        .whiskers(iqr(1.5))
                        .width(width)
                        .height(height)
                        .tickFormat(#{ ca[:axis_tick_format] });

          var data = #{ ca[:values].to_json };

          chart.domain([min, max]);

          var svg = d3.select("##{ dom_id }").selectAll("svg")
                      .data(data)
                    .append("g")
                      .attr("transform", "rotate(90) translate(" + (width + margin.left) + " -" + (height + margin.bottom) + ")")
                      .call(chart);

          // Function to compute the interquartile range.
          function iqr(k) {
            return function(d, i) {
              var q1 = d.quartiles[0],
                  q3 = d.quartiles[2],
                  iqr = (q3 - q1) * k,
                  i = -1,
                  j = d.length;
              while (d[++i] < q1 - iqr);
              while (d[--j] > q3 + iqr);
              return [i, j];
            };
          }
        })();
      </script>
    </div>
  )
end