I have managed to create a line chart in d3 but now need to overlay a couple of horizontal lines and vertical lines. Here is what the chart looks like:
Here is the code:
JavaScript
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<!DOCTYPE html> <meta charset="utf-8"> <style> body { font: 14px sans-serif; } .axis path, .axis line { fill: none; stroke: #000; stroke-width: 1.5px; shape-rendering: crispEdges; } .line { fill: none; stroke: steelblue; stroke-width: 3.5px; } .dot { stroke: blue; } .grid .tick { stroke: lightgrey; opacity: 0.7; } </style> <body> <script src="https://d3js.org/d3.v3.js"></script> <script> var tests = <?php echo $tests; ?>; console.log("tests=" +JSON.stringify(tests)); var events = <?php echo $events; ?>; console.log("events=" +JSON.stringify(events)); var margin = {top: 50, right: 20, bottom: 60, left: 90}, width = 900 - margin.left - margin.right, height = 400 - margin.top - margin.bottom; var x = d3.time.scale() .range([0, width]); var y = d3.scale.linear() .range([height, 0]); var xAxis = d3.svg.axis() .scale(x) .ticks(d3.time.years,1) //makes the xAxis ticks a little longer than the xMinorAxis ticks .tickSize(10) .orient("bottom"); var xMinorAxis = d3.svg.axis() .scale(x) .ticks(d3.time.months,1) .orient("bottom"); var yAxis = d3.svg.axis() .scale(y) .orient("left"); var line = d3.svg.line() .x(function(d) { return x(d.date); }) .y(function(d) { return y(d.total_km); }); var svg = d3.select("body").append("svg") .attr("width", width + margin.left + margin.right) .attr("height", height + margin.top + margin.bottom) .append("g") .attr("transform", "translate(" + margin.left + "," + margin.top + ")"); // function for the y grid lines function make_y_axis() { return d3.svg.axis() .scale(y) .orient("left") .ticks(5) //somehow this makes the y-axis grid draw every other line, rather than every line } var data = []; function DataPoint(x,y) { this.date_time = x; this.total_km = y; } var lowerLimit; var upperLimit; function loadData() { for (i=1; i < tests.length; i++) { var test = tests[i]; console.log("x="+test[0]+", y="+test[1]); data.push(new DataPoint(test[0],test[1])); lowerLimit = test[2]; upperLimit = test[3]; } } loadData(); console.log("data1="+JSON.stringify(data)); function processData(data) { data.forEach(function(d) { console.log("d.date_time="+d.date_time +", d.total_km="+d.total_km); d.date = new Date(d.date_time); console.log("d.date=" +d.date); }); //using imported data to define extent of x and y domains x.domain(d3.extent(data, function(d) { return d.date; })); y.domain(d3.extent(data, function(d) { return d.total_km; })); // Draw the y Grid lines svg.append("g") .attr("class", "grid") .call(make_y_axis() .tickSize(-width, 0, 0) //causes the line to be drawn the full width of the chart .tickFormat("") ) //draw the data line svg.append("path") .datum(data) .attr("class", "line") .attr("d", line); //draw the upper limit var minDate = new Date(data[0].date_time); console.log("minDate="+minDate +", x(minDate)="+x(minDate)); var maxDate = new Date(data[data.length-1].date_time); console.log("maxDate="+maxDate +", x(maxDate)="+x(maxDate)); svg.append("line") .attr("class", "x") .style("stroke", "red") .style("stroke-dasharray", "3,3") .style("opacity", 0) .attr("x1", x(minDate)) .attr("y1", y(upperLimit)) .attr("x2", x(maxDate)) .attr("y2", y(upperLimit)); //creating a group(g) and will append a circle and 2 lines inside each group var g = svg.selectAll() .data(data).enter().append("g"); //The markers on the line g.append("circle") //circle radius is increased .attr("r", 4.5) .attr("cx", function(d) { return x(d.date); }) .attr("cy", function(d) { return y(d.total_km); }); svg.append("g") .attr("class", "x axis") .attr("transform", "translate(0," + height + ")") .call(xAxis) .selectAll(".tick text") .call(wrap, 35); svg.append("g") .attr("class","xMinorAxis") .attr("transform", "translate(0," + height + ")") .style({ 'stroke': 'Black', 'fill': 'none', 'stroke-width': '1px'}) .call(xMinorAxis) .selectAll("text").remove(); svg.append("text") // text label for the x-axis .attr("x", width / 2 ) .attr("y", height + margin.bottom) .style("text-anchor", "middle") .text("Date"); svg.append("text") // text label for the y-axis .attr("y",30 - margin.left) .attr("x",50 - (height / 2)) .attr("transform", "rotate(-90)") .style("text-anchor", "end") .style("font-size", "16px") .text("Tryglycerides (mg/dL)"); svg.append("text") // text label for chart Title .attr("x", width / 2 ) .attr("y", 0 - (margin.top/2)) .style("text-anchor", "middle") .style("font-size", "16px") .style("text-decoration", "underline") .text("Tryglyceride Levels"); svg.append("g") .attr("class", "y axis") .call(yAxis) }; processData(data);</script>I want to create horizontal line at 149 for the upper limit where you want the triglyceride levels to be below. I try to create that line in the “draw the upper limit” section. But no line is drawn.
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Answer
Well I’m not real happy with this solution, but it works. Could not figure out why the svg.append(“line”) command failed to display a line, so I used the svg.append(“path”) command instead. I added the following code:
JavaScript
var data2 = [];data2.push(new DataPoint(data[0].date_time,149));data2.push(new DataPoint(data[data.length-1].date_time,149));svg.append("path") .datum(data2) .attr("d", line) .style("stroke", "red") .style("stroke-dasharray", "3,3")Then I modified the DataPoint code to this:
JavaScript
function DataPoint(x,y) { this.date_time = x; this.date = new Date(x); this.total_km = y;}Now the chart has a red dashed line representing the tryglyceride upper limit:
