D3 Examples - D3: Unit Bar Chart with Brush and Zoom

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<!DOCTYPE html>
<meta charset="utf-8">
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<style type="text/css">
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body {
  font-family: avenir next, sans-serif;
  font-size: 12px;
}
​
.zoom {
  cursor: move;
  fill: none;
  pointer-events: all;
}
​
circle {
  fill: #FF7700;
  fill-opacity: 0.4;
}
​
.axis {
  stroke-width: 0.5px;
  stroke: #888;
  font: 10px avenir next, sans-serif;
}
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.axis > path {
  stroke: #888;
}
​
​
</style>
​
<body>
</body>
​
<script src="https://d3js.org/d3.v4.min.js"></script>
<script>
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/* Adapted from: https://bl.ocks.org/mbostock/34f08d5e11952a80609169b7917d4172 */
​
var margin = {top: 20, right: 20, bottom: 90, left: 50},
    margin2 = {top: 230, right: 20, bottom: 30, left: 50},
    width = 960 - margin.left - margin.right,
    height = 300 - margin.top - margin.bottom,
    height2 = 300 - margin2.top - margin2.bottom;
​
var parseTime = d3.timeParse("%Y-%m-%d");
​
var x = d3.scaleTime().range([0, width]),
    x2 = d3.scaleTime().range([0, width]),
    y = d3.scaleLinear().range([height, 0]),
    y2 = d3.scaleLinear().range([height2, 0]);
​
var xAxis = d3.axisBottom(x).tickSize(0),
    xAxis2 = d3.axisBottom(x2).tickSize(0),
    yAxis = d3.axisLeft(y).tickSize(0);
​
var brush = d3.brushX()
    .extent([[0, 0], [width, height2]])
    .on("brush", brushed);
​
var zoom = d3.zoom()
    .scaleExtent([1, Infinity])
    .translateExtent([[0, 0], [width, height]])
    .extent([[0, 0], [width, height]])
    .on("zoom", zoomed);
​
var svg = d3.select("body").append("svg")
    .attr("width", width + margin.left + margin.right)
    .attr("height", height + margin.top + margin.bottom);
​
svg.append("defs").append("clipPath")
    .attr("id", "clip")
  .append("rect")
    .attr("width", width)
    .attr("height", height);
​
var focus = svg.append("g")
    .attr("class", "focus")
    .attr("transform", "translate(" + margin.left + "," + margin.top + ")");
​
var context = svg.append("g")
    .attr("class", "context")
    .attr("transform", "translate(" + margin2.left + "," + margin2.top + ")");
​
// Data Load from CSV
d3.csv("message_history.csv", function(error, data) {
  if(error) throw error;
​
  data.forEach(function(d) {
    d.sent_time = parseTime(d.sent_time);
  });
​
  var xMin = d3.min(data, function(d) { return d.sent_time; });
  var yMax = Math.max(20, d3.max(data, function(d) { return d.messages_sent_in_day; }));
​
  x.domain([xMin, new Date()]);
  y.domain([0, yMax]);
  x2.domain(x.domain());
  y2.domain(y.domain());
​
  var num_messages = function(dataArray, domainRange) { return d3.sum(dataArray, function(d) {
    return d.sent_time >= domainRange.domain()[0] && d.sent_time <= domainRange.domain()[1];
    })
  }
​
  // append scatter plot to main chart area
  var messages = focus.append("g");
    messages.attr("clip-path", "url(#clip)");
    messages.selectAll("message")
        .data(data)
        .enter().append("circle")
        .attr('class', 'message')
        .attr("r", 4)
        .style("opacity", 0.4)
        .attr("cx", function(d) { return x(d.sent_time); })
        .attr("cy", function(d) { return y(d.messages_sent_in_day); })
​
  focus.append("g")
        .attr("class", "axis x-axis")
        .attr("transform", "translate(0," + height + ")")
        .call(xAxis);
​
  focus.append("g")
        .attr("class", "axis axis--y")
        .call(yAxis);
​
  // Summary Stats
  focus.append("text")
        .attr("transform", "rotate(-90)")
        .attr("y", 0 - margin.left)
        .attr("x",0 - (height / 2))
        .attr("dy", "1em")
        .style("text-anchor", "middle")
        .text("Messages (in the day)");
​
  focus.append("text")
        .attr("x", width - margin.right)
        .attr("dy", "1em")
        .attr("text-anchor", "end")
        .text("Messages: " + num_messages(data, x));
​
  svg.append("text")
        .attr("transform",
              "translate(" + ((width + margin.right + margin.left)/2) + " ," +
                             (height + margin.top + margin.bottom) + ")")
        .style("text-anchor", "middle")
        .text("Date");
​
  svg.append("rect")
    .attr("class", "zoom")
    .attr("width", width)
    .attr("height", height)
    .attr("transform", "translate(" + margin.left + "," + margin.top + ")")
    .call(zoom);
​
  // append scatter plot to brush chart area
   var messages = context.append("g");
       messages.attr("clip-path", "url(#clip)");
       messages.selectAll("message")
          .data(data)
          .enter().append("circle")
          .attr('class', 'messageContext')
          .attr("r",3)
          .style("opacity", .6)
          .attr("cx", function(d) { return x2(d.sent_time); })
          .attr("cy", function(d) { return y2(d.messages_sent_in_day); })
​
  context.append("g")
        .attr("class", "axis x-axis")
        .attr("transform", "translate(0," + height2 + ")")
        .call(xAxis2);
​
  context.append("g")
        .attr("class", "brush")
        .call(brush)
        .call(brush.move, x.range());
​
  });
​
//create brush function redraw scatterplot with selection
function brushed() {
  if (d3.event.sourceEvent && d3.event.sourceEvent.type === "zoom") return; // ignore brush-by-zoom
  var s = d3.event.selection || x2.range();
  x.domain(s.map(x2.invert, x2));
  focus.selectAll(".message")
        .attr("cx", function(d) { return x(d.sent_time); })
        .attr("cy", function(d) { return y(d.messages_sent_in_day); });
  focus.select(".x-axis").call(xAxis);
  svg.select(".zoom").call(zoom.transform, d3.zoomIdentity
      .scale(width / (s[1] - s[0]))
      .translate(-s[0], 0));
    var e = d3.event.selection;
  var selectedMessages = focus.selectAll('.message').filter(function(){ 
    var xValue = this.getAttribute('cx');
    return e[0] <= xValue && xValue <= e[1];
  });
  console.log(selectedMessages.nodes().length);
}
​
function zoomed() {
  if (d3.event.sourceEvent && d3.event.sourceEvent.type === "brush") return; // ignore zoom-by-brush
  var t = d3.event.transform;
  x.domain(t.rescaleX(x2).domain());
  focus.selectAll(".message")
        .attr("cx", function(d) { return x(d.sent_time); })
        .attr("cy", function(d) { return y(d.messages_sent_in_day); });
  focus.select(".x-axis").call(xAxis);
  context.select(".brush").call(brush.move, x.range().map(t.invertX, t));
}
​
</script>
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