TD2-CHEUNG-KaHei

forked from romsson's block: simple line chart from dataset Kei

<!DOCTYPE html>
<head>
  <meta charset="utf-8">
  <script src="https://d3js.org/d3.v4.min.js"></script>
  <style>
    .line {
      fill: none;
      stroke: black;
      stroke-width: 1.5px;
    }
  </style>
</head>

<body>
  <script>
    // SVG canvas size
    var svg = d3.select("body").append("svg")
      .attr("width", 960)
      .attr("height", 500);

var width = 800;
    var height = 400;

// Format of dates
    // See formats https://bl.ocks.org/zanarmstrong/raw/05c1e95bf7aa16c4768e/
    // Data sample {"name": "G", "value": 10, "date": "2016-07"}
    var parseDate = d3.timeParse("%Y-%m");
    var displayDate = d3.timeFormat("%b %y");
    var displayValue = d3.format(",.0f");
    
    
    // Scale the data to the graph size
    // Ordinal scale
    var x = d3.scaleTime()
        .range([0, width]);
    
    // Linear scale
    // Fluctuation significance factor of the line
    var y = d3.scaleLinear()
        .range([height, height - 200]);

// Coordinates of the line points
    var line = d3.line()
        .x(function(d) { return x(d.date); })
        .y(function(d) { return y(d.value); });
    
    // Displacement of the line. Here 50 px to the right
    var g = svg.append("g")
    	.attr("transform", "translate(50, 0)")
    
   	d3.json("dataset.json", function(error, data) {
	  	if (error) throw error;
      
      // Pre-processing
      data.forEach(function(d) {
				d.value = +d.value; // Parse data values into absolute positive values.
        d["date"] = parseDate(d["date"]); // Parse data dates into dates.
      });
      
      // Return all data values, capture the max and min, fix them to the range of axes
      x.domain(d3.extent(data, function(d) { return d.date; }));
			y.domain([0, d3.max(data, function(d) { return d.value; })]);

// x-axis labels
      svg.selectAll(".label").data(data).enter()
       .append("text")
      	.attr("class", "label")
        .text(function(d, i) { return displayDate(d.date); })
        .attr("y", 420)
        .attr("x", function(d) { return x(d.date); })
        .style("font-size", 10)
        .style("font-family", "monospace");

// Text value overview
      g.selectAll(".value").data(data).enter()
         .append("text")
         .text(function(d, i) { return displayValue(d.value); })
         .attr("class", "snap")
         .attr("x", function(d) { return x(d.date) + 5; })
         .attr("y", function(d) { return y(d.value) - 20; })
         .style("display", "none");
      
      // Display last value
      g.selectAll(".value").data([data[data.length -1]]).enter()
       .append("text")
        .text(function(d, i) { return displayValue(d.value); })
        .attr("class", "value")
        .attr("y", function(d) { return y(d.value); })
        .attr("x", width + 40)
        .style("font-size", 20)
        .style("font-family", "monospace");

// Path
      g.selectAll(".line").data([data]).enter().append("path")
        .attr("class", "line")
        .attr("d", line);
      
      // Invisible dashed line
      g.selectAll("line").data(data).enter().append("line")	
        .attr("x1", function(d) { return x(d.date); })
        .attr("y1", function(d) { return y(d.value); })
        .attr("x2", function(d) { return x(d.date); })
        .attr("y2", function(d) { return y(0); })
        .attr("stroke", "none")
        .attr("stroke-width", 1)
        .style("stroke-dasharray", ("3, 3"))
      
      // Grey polka dots at points
      g.selectAll("circle").data(data).enter()
        .append("circle")
         .attr("cx", function(d) { return x(d.date); })
         .attr("cy", function(d) { return y(d.value); })
         .attr("r", 10)
         .style("fill", "#000000")
         .attr("opacity", 0.2)
      
      // Mouseover
       .on("mouseover", function(d) {
        
        // Fill polka dot red
        d3.select(this).style("fill", "#ff0000")
                       .attr("opacity", 1);
        // Show concerned text value overview
        d3.selectAll(".snap").filter(function(e) { return d === e; })
                             .style("display", "block");
        // Show corresponding dashed line
        d3.selectAll("line").filter(function(e) { return d === e; })
                             .attr("stroke", "#000000");
      })
      
      // Mouseout
       // Fill polka dot grey
       .on("mouseout", function(d, i) {
        d3.select(this).style("fill", "#000000")
                       .attr("opacity", 0.2);
        // Hide concerned text value overview
        d3.selectAll(".snap").filter(function(e) { return d === e; })
                             .style("display", "none");
        // Hide dashed line
        d3.selectAll("line").filter(function(e) { return d === e; })
                             .attr("stroke", "none");
      })
    });

</script>
</body>

https://d3js.org/d3.v4.min.js