gurjeet · February 26, 2018 03:23
diff --git a/index.html b/index.html

 <!--
 Visit the following URL to see the rendered HTML:

 https://bl.ocks.org/gurjeet/83189e2931d053187eab52887a870c5e
 -->
 <!DOCTYPE html>
 <html>
  <head>
    <title>Barchart Demo</title>
    <script src="https://d3js.org/d3.v4.min.js"></script>
  </head>
  <body>
 	  
    <svg></svg>
    <script>
      var data = [100, -100, -150, 55, 150, 120, 450, 980, 1200];

      var leftMargin = 50;  // Space to the left of first bar; accomodates y-axis labels
      var rightMargin = 10; // Space to the right of last bar
      var margin = {left: leftMargin, right: rightMargin, top: 10, bottom: 10};
      var barWidth = 30;  // Width of the bars
      var chartHeight = 450;  // Height of chart, from x-axis (ie. y=0)
      var chartWidth = margin.left + data.length * barWidth + margin.right;

      /* This scale produces negative output for negatve input */
      var yScale = d3.scaleLinear()
                     .domain([0, d3.max(data)])
                     .range([0, chartHeight]);

      /*
       * We need a different scale for drawing the y-axis. It needs
       * a reversed range, and a larger domain to accomodate negaive values.
       */
      var yAxisScale = d3.scaleLinear()
                         .domain([d3.min(data), d3.max(data)])
                         .range([chartHeight - yScale(d3.min(data)), 0 ]);

      var svg = d3.select('svg');
      svg
          .attr('height', chartHeight + 100)
          .attr('width', chartWidth)
          .style('border', '1px solid');

      svg
        .selectAll("rect")
        .data(data)
        .enter()
        .append("rect")
          .attr("x", function(d, i) { return margin.left + i * barWidth; })
          .attr("y", function(d, i) { return chartHeight - Math.max(0, yScale(d));})
          .attr("height", function(d) { return Math.abs(yScale(d)); })
          .attr("width", barWidth)
          .style("fill", "grey")
 		  .style("stroke", "black")
 		  .style("stroke-width", "1px")
 		  .style("opacity", function(d, i) { return 1 /*- (i * (1/data.length)); */});

      var yAxis = d3.axisLeft(yAxisScale);
      
      svg.append('g')
        .attr('transform', function(d) {
          return 'translate(' + margin.left + ', 0)';
        })
        .call(yAxis);

      /*
      var xScale = d3.scaleLinear()
                      .domain(0, data.length * barWidth)
                      .range(0, chartWidth);

      var xAxis = d3.axisBottom();
      */
      
    </script>
  </body>
 </html>

	<!--
	Visit the following URL to see the rendered HTML:

	https://bl.ocks.org/gurjeet/83189e2931d053187eab52887a870c5e
	-->
	<!DOCTYPE html>
	<html>
	<head>
	<title>Barchart Demo</title>
	<script src="https://d3js.org/d3.v4.min.js"></script>
	</head>
	<body>

	<svg></svg>
	<script>
	var data = [100, -100, -150, 55, 150, 120, 450, 980, 1200];

	var leftMargin = 50; // Space to the left of first bar; accomodates y-axis labels
	var rightMargin = 10; // Space to the right of last bar
	var margin = {left: leftMargin, right: rightMargin, top: 10, bottom: 10};
	var barWidth = 30; // Width of the bars
	var chartHeight = 450; // Height of chart, from x-axis (ie. y=0)
	var chartWidth = margin.left + data.length * barWidth + margin.right;

	/* This scale produces negative output for negatve input */
	var yScale = d3.scaleLinear()
	.domain([0, d3.max(data)])
	.range([0, chartHeight]);

	/*
	* We need a different scale for drawing the y-axis. It needs
	* a reversed range, and a larger domain to accomodate negaive values.
	*/
	var yAxisScale = d3.scaleLinear()
	.domain([d3.min(data), d3.max(data)])
	.range([chartHeight - yScale(d3.min(data)), 0 ]);

	var svg = d3.select('svg');
	svg
	.attr('height', chartHeight + 100)
	.attr('width', chartWidth)
	.style('border', '1px solid');

	svg
	.selectAll("rect")
	.data(data)
	.enter()
	.append("rect")
	.attr("x", function(d, i) { return margin.left + i * barWidth; })
	.attr("y", function(d, i) { return chartHeight - Math.max(0, yScale(d));})
	.attr("height", function(d) { return Math.abs(yScale(d)); })
	.attr("width", barWidth)
	.style("fill", "grey")
	.style("stroke", "black")
	.style("stroke-width", "1px")
	.style("opacity", function(d, i) { return 1 /- (i (1/data.length)); */});

	var yAxis = d3.axisLeft(yAxisScale);

	svg.append('g')
	.attr('transform', function(d) {
	return 'translate(' + margin.left + ', 0)';
	})
	.call(yAxis);

	/*
	var xScale = d3.scaleLinear()
	.domain(0, data.length * barWidth)
	.range(0, chartWidth);

	var xAxis = d3.axisBottom();
	*/

	</script>
	</body>
	</html>