D3 Examples - Chained Transitions

Chained Transitions
This variation of a line chart demonstrates a sequence of chained transitions. Clicking on the radio buttons changes the displayed metric. First, the line transitions to the new values. Then, the axes rescale to fit the new data.
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<!DOCTYPE html>
<meta charset="utf-8">
<style>
​
body {
  font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
  margin: auto;
  position: relative;
  width: 960px;
}
​
text {
  font: 10px sans-serif;
}
​
.axis path,
.axis line {
  fill: none;
  stroke: #000;
  shape-rendering: crispEdges;
}
​
.x.axis path {
  display: none;
}
​
.line {
  fill: none;
  stroke: steelblue;
  stroke-width: 1.5px;
}
​
form {
  position: absolute;
  right: 10px;
  top: 10px;
}
​
</style>
<form>
  <label><input type="radio" name="city" value="New York" checked> New York</label>
  <label><input type="radio" name="city" value="San Francisco"> San Francisco</label>
</form>
<script src="//d3js.org/d3.v4.min.js"></script>
<script>
​
var margin = {top: 20, right: 80, bottom: 30, left: 50},
    width = 960 - margin.left - margin.right,
    height = 500 - margin.top - margin.bottom;
​
var city = "New York",
    parseDate = d3.timeParse("%Y%m%d");
​
var x = d3.scaleTime()
    .range([0, width]);
​
var y = d3.scaleLinear()
    .range([height, 0]);
​
var xAxis = d3.axisBottom()
    .scale(x);
​
var yAxis = d3.axisLeft()
    .scale(y);
​
var line = d3.line()
    .curve(d3.curveBasis)
    .x(function(d) { return x(d.date); })
    .y(function(d) { return y(d[city]); });
​
var color = d3.scaleOrdinal(d3.schemeCategory10 )
        .domain(["New York", "San Francisco"])
        
  
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 + ")");
​
d3.tsv("data.tsv", function(error, data) {
  if (error) throw error;
​
  data.forEach(function(d) {
    d.date = parseDate(d.date);
    d["New York"] = +d["New York"];
    d["San Francisco"] = +d["San Francisco"];
  });
​
  x.domain([data[0].date, data[data.length - 1].date]);
  y.domain(d3.extent(data, function(d) { return d[city]; }));
​
  svg.append("g")
      .attr("class", "x axis")
      .attr("transform", "translate(0," + height + ")")
      .call(xAxis);
​
  svg.append("g")
      .attr("class", "y axis")
      .call(yAxis)
    .append("text")
      .attr("transform", "rotate(-90)")
      .attr("y", 6)
      .attr("dy", ".71em")
      .style("text-anchor", "end")
      .text("Temperature (ºF)");
​
  svg.append("path")
      .datum(data)
      .attr("class", "line")
      .attr("d", line);
  
  svg.append("text")
      .datum(data[data.length - 1])
      .attr("class", "label")
      .attr("transform", transform)
      .attr("x", 3)
      .attr("dy", ".35em")
      .text(city);
​
  d3.selectAll("input").on("change", change);
​
  var timeout = setTimeout(function() {
    d3.select("input[value=\"San Francisco\"]").property("checked", true).each(change);
  }, 2000);
​
  console.clear()
  
  function change() {
    
    clearTimeout(timeout);
        var oldCity = city,
        newCity = this.value;
    
    // First transition the y-axis to the combined extent 
    y.domain(d3.extent(d3.merge([
      d3.extent(data, function(d) { return d[oldCity]; }),
      d3.extent(data, function(d) { return d[newCity]; })
    ])));
        
    console.log(city + " -(0)-> " + newCity, y.domain())
    
    var t0 = svg.transition().duration(750);
    t0.selectAll(".line").attr("d", line);
    t0.selectAll(".label").attr("transform", transform);
    t0.selectAll(".y.axis").call(yAxis);
    
    city = this.value;
​
    console.log(oldCity + " -(1)-> " + newCity, y.domain())
    
    // Then transition the line & label to the new city.
    var t1 = t0.transition();
    t1.selectAll(".line").attr("d", line).style("stroke", color(newCity));
    t1.selectAll(".label").attr("transform", transform).text(newCity);
​
    // Then transition the y-axis to the new city's range.
    y.domain(d3.extent(data, function(d) { return d[newCity]; }));
    
    console.log(oldCity + " -(2)-> " + newCity, y.domain())
    
    var t2 = t1.transition();
    t2.selectAll(".line").attr("d", line);
    t2.selectAll(".label").attr("transform", transform);
    t2.selectAll(".y.axis").call(yAxis);
  }
​
  function transform(d) {
    return "translate(" + x(d.date) + "," + y(d[city]) + ")";
  }
});
​
</script>
​
    