text: /* ------------------------------------------------------------------------------
   *
   *  # D3.js - gradient encoding line chart
   *
   *  Demo d3.js gradient encoding line chart setup with .tsv data source
   *
   * ---------------------------------------------------------------------------- */
  
  
  // Setup module
  // ------------------------------
  
  var D3LineGradient = function() {
  
  
      //
      // Setup module components
      //
  
      // Chart
      var _lineGradient = function() {
          if (typeof d3 == 'undefined') {
              console.warn('Warning - d3.min.js is not loaded.');
              return;
          }
  
          // Main variables
          var element = document.getElementById('d3-line-gradient'),
              height = 400;
  
  
          // Initialize chart only if element exsists in the DOM
          if(element) {
  
              // Basic setup
              // ------------------------------
  
              // Define main variables
              var d3Container = d3.select(element),
                  margin = {top: 5, right: 20, bottom: 20, left: 40},
                  width = d3Container.node().getBoundingClientRect().width - margin.left - margin.right,
                  height = height - margin.top - margin.bottom - 5;
  
              // Format data
              var parseDate = d3.time.format("%Y%m%d").parse;
  
              // Colors
              var color1 = '#4CAF50',
                  color2 = '#FF5722';
  
  
  
              // Construct scales
              // ------------------------------
  
              // Horizontal
              var x = d3.time.scale()
                  .range([0, width]);
  
              // Vertical
              var y = d3.scale.linear()
                  .range([height, 0]);
  
  
  
              // Create axes
              // ------------------------------
  
              // Horizontal
              var xAxis = d3.svg.axis()
                  .scale(x)
                  .orient("bottom")
                  .ticks(7)
                  .tickFormat(d3.time.format("%b"));
  
              // Vertical
              var yAxis = d3.svg.axis()
                  .scale(y)
                  .orient("left");
  
  
  
              // Create chart
              // ------------------------------
  
              // Add SVG element
              var container = d3Container.append("svg");
  
              // Add SVG group
              var svg = container
                  .attr("width", width + margin.left + margin.right)
                  .attr("height", height + margin.top + margin.bottom)
                  .append("g")
                      .attr("transform", "translate(" + margin.left + "," + margin.top + ")");
  
  
              // Construct chart layout
              // ------------------------------
  
              // Line
              var line = d3.svg.line()
                  .interpolate("basis")
                  .x(function(d) { return x(d.date); })
                  .y(function(d) { return y(d.temperature); });
  
  
              // Load data
              // ------------------------------
  
              d3.tsv("../../../../global_assets/demo_data/d3/lines/lines_gradient.tsv", function(error, data) {
  
                  // Pull out values
                  data.forEach(function(d) {
                      d.date = parseDate(d.date);
                      d.temperature = +d.temperature;
                  });
  
  
                  // Set input domains
                  // ------------------------------
  
                  // Horizontal
                  x.domain([data[0].date, data[data.length - 1].date]);
  
                  // Vertical
                  y.domain(d3.extent(data, function(d) { return d.temperature; }));
  
  
                  //
                  // Append chart elements
                  //
  
                  // Add gradient
                  svg.append("linearGradient")
                      .attr("id", "temperature-gradient")
                      .attr("gradientUnits", "userSpaceOnUse")
                      .attr("x1", 0)
                      .attr("y1", y(50))
                      .attr("x2", 0)
                      .attr("y2", y(60))
                      .selectAll("stop")
                      .data([
                          {offset: "0%", color: color1},
                          {offset: "100%", color: color2}
                      ])
                      .enter()
                      .append("stop")
                          .attr("offset", function(d) { return d.offset; })
                          .attr("stop-color", function(d) { return d.color; });
  
                  // Add line
                  svg.append("path")
                      .datum(data)
                      .attr("class", "d3-line d3-line-medium")
                      .attr("stroke", "url(#temperature-gradient)")
                      .attr("d", line);
  
  
  
                  // Append axes
                  // ------------------------------
  
                  // Horizontal
                  svg.append("g")
                      .attr("class", "d3-axis d3-axis-horizontal")
                      .attr("transform", "translate(0," + height + ")")
                      .call(xAxis);
  
                  // Vertical
                  var verticalAxis = svg.append("g")
                      .attr("class", "d3-axis d3-axis-vertical")
                      .call(yAxis);
  
                  // Add text label
                  verticalAxis.append("text")
                      .attr("class", "d3-axis-title")
                      .attr("transform", "rotate(-90)")
                      .attr("y", 10)
                      .attr("dy", ".71em")
                      .style("text-anchor", "end")
                      .text("Temperature (ºF)");
              });
  
  
  
              // Resize chart
              // ------------------------------
  
              // Call function on window resize
              window.addEventListener('resize', resize);
  
              // Call function on sidebar width change
              var sidebarToggle = document.querySelectorAll('.sidebar-control');
              if (sidebarToggle) {
                  sidebarToggle.forEach(function(togglers) {
                      togglers.addEventListener('click', resize);
                  });
              }
  
              // Resize function
              // 
              // Since D3 doesn't support SVG resize by default,
              // we need to manually specify parts of the graph that need to 
              // be updated on window resize
              function resize() {
  
                  // Layout variables
                  width = d3Container.node().getBoundingClientRect().width - margin.left - margin.right;
  
  
                  // Layout
                  // -------------------------
  
                  // Main svg width
                  container.attr("width", width + margin.left + margin.right);
  
                  // Width of appended group
                  svg.attr("width", width + margin.left + margin.right);
  
  
                  // Axes
                  // -------------------------
  
                  // Horizontal range
                  x.range([0, width]);
  
                  // Horizontal axis
                  svg.selectAll('.d3-axis-horizontal').call(xAxis);
  
  
                  // Chart elements
                  // -------------------------
  
                  // Line path
                  svg.selectAll('.d3-line').attr("d", line);
              }
          }
      };
  
  
      //
      // Return objects assigned to module
      //
  
      return {
          init: function() {
              _lineGradient();
          }
      }
  }();
  
  
  // Initialize module
  // ------------------------------
  
  document.addEventListener('DOMContentLoaded', function() {
      D3LineGradient.init();
  });
  