D3 Examples - Margin Convention Encapsulation Idea

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<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width">
    <script src="https://d3js.org/d3.v4.min.js"></script>
    <title>Basic Scatter Plot</title>
  </head>
  <body>
    <svg width="960" height="500"></svg>
    <script>
      
      d3.margin = (selection, {width, height, margin, children}) => {
        let g = selection.selectAll('margin-group').data([null]);
        g = g.enter().append('g').attr('class', 'margin-group')
          .merge(g)
            .attr('transform', `translate(${margin.left}, ${margin.top})`);
        
        children(g, {
          innerWidth: width - margin.left - margin.right,
          innerHeight: height - margin.top - margin.bottom
        })
      };
      
    </script>
    <script>
      const xValue = d => d.sepalLength;
      const yValue = d => d.petalLength;
      
      const xScale = d3.scaleLinear();
      const yScale = d3.scaleLinear();
​
      const svg = d3.select('svg');
      
      const row = d => {
        d.petalLength = +d.petalLength;
        d.petalWidth = +d.petalWidth;
        d.sepalLength = +d.sepalLength;
        d.sepalWidth = +d.sepalWidth;
        return d;
      };
​
      d3.csv('iris.csv', row, data => {
        xScale.domain(d3.extent(data, xValue));
        yScale.domain(d3.extent(data, yValue));
        
        d3.margin(svg, {
          width: svg.attr('width'),
          height: svg.attr('height'),
          margin: { left: 20, right: 20, top: 20, bottom: 20 },
          children: (g, {innerWidth, innerHeight}) => {
            xScale.range([0, innerWidth]);
            yScale.range([innerHeight, 0]);
            
            g.selectAll('circle').data(data)
              .enter().append('circle')
                .attr('cx', d => xScale(xValue(d)))
                .attr('cy', d => yScale(yValue(d)))
                .attr('r', 8);
          }
        });
      });
    </script>
  </body>
</html>
​
    