Box Plot w/ Brushing

README.md

A boxplot containing monthly values x 10 years, with brushing by year to highlight individual values (points) from that year, as well as brushing by value (point) to highlight both corresponding year and other values (points) from that year.

brushboxplot.js

//initialize the dimensions
var margin = {top: 10, right: 10, bottom: 10, left: 10},
    width = 400 - margin.left - margin.right,
    height = 100 - margin.top - margin.bottom,
    padding = 20
    midline = (height - padding) / 2;

//initialize the x scale
var xScale = d3.scale.linear()
               .range([padding, width - padding]);  

//initialize the x axis
var xAxis = d3.svg.axis()
              .scale(xScale)
              .orient("bottom");

var parseDate = d3.time.format("%b %Y").parse;

//initialize the time scale
var timeScale = d3.scale.linear()
                  .range([padding / 2, width - padding / 2]);

//initialize boxplot statistics
var data = [],
    outliers = [],
    minVal = Infinity,
    lowerWhisker = Infinity,
    q1Val = Infinity,
    medianVal = 0,
    q3Val = -Infinity,
    iqr = 0,
    upperWhisker = -Infinity,
    maxVal = -Infinity;

// initialize time stats
var yearArr = [],
    dates = []
    selectedYear = 0;

d3.csv("data.csv", type, function(error,csv) { // load the data
  
  data = csv.map(function(d) {
    return d.value;
  });

  data = data.sort(d3.ascending);

  //calculate the boxplot statistics
  minVal = data[0],
  q1Val = d3.quantile(data, .25),
  medianVal = d3.quantile(data, .5),
  q3Val = d3.quantile(data, .75),
  iqr = q3Val - q1Val,
  maxVal = data[data.length - 1];

  var index = 0;

  //search for the lower whisker, the mininmum value within q1Val - 1.5*iqr
  while (index < data.length && lowerWhisker == Infinity) {

    if (data[index] >= (q1Val - 1.5*iqr))
      lowerWhisker = data[index];
    else
      outliers.push(data[index]);
    index++;
  }

  index = data.length-1; // reset index to end of array

  //search for the upper whisker, the maximum value within q1Val + 1.5*iqr
  while (index >= 0 && upperWhisker == -Infinity) {

    if (data[index] <= (q3Val + 1.5*iqr))
      upperWhisker = data[index];
    else
      outliers.push(data[index]);
    index--;
  }

  dates = csv.map(function(d) {
    return d.date;
  });

  for (i = 0; i < dates.length; i++) {

    // get year
    var year = parseDate(dates[i]).getFullYear();

    if (!(yearArr.indexOf(year) > -1))
      yearArr.push(year);
  }

  yearArr = yearArr.sort(d3.ascending);
 
  //map the domain to the x scale +10%
  xScale.domain([0,maxVal*1.10]);

  //map the time scale
  timeScale.domain([yearArr[0],yearArr[yearArr.length-1]+1]);

  var datesvg = d3.select("body")
                  .append("svg")
                  .attr("width", width)
                  .attr("height", height);

  //time intervals as rect+label texts
  intervals = datesvg.append("g")
                         .selectAll("g")
                         .data(yearArr)     
                         .enter(); 
     
  //add linked highlighting to points on interval mouseover
  intervalCell = intervals.append("g")
                          .attr("class", "intervalCell")                          
                          .on("mouseover", function(d) {
                            d3.selectAll(".year"+d)
                              .attr("class", "selected");
                          })
                          .on("mouseout", function(d) {
                            d3.selectAll(".selected")
                              .attr("class", "year"+d); 
                          }); 

  intervalCell.append("rect")
              .attr("x", function(d){
               return timeScale(d)
              })
              .attr("id", function(d){
               return "interval" + d;
              }) 
              .attr("y", 0)
              .attr("width", (width - padding) / yearArr.length - 2)
              .attr("height", height - padding);

  // text labels for interval cells
  intervalCell.append("text")
              .attr("x", function(d){
               return timeScale(d) + 5
              })
              .attr("width", (width - padding) / yearArr.length - 8)
              .attr("height", 10)
              .attr("y", midline + 2.5)
              .attr("font-family", "sans-serif")
              .attr("font-size", "10px")
              .attr("class", "intervalLabel")
              .text(function(d) { return d});  

  var svg = d3.select("body")
              .append("svg")
              .attr("width", width)
              .attr("height", height);

  //append the axis
  svg.append("g")
     .attr("class", "axis")
     .attr("transform", "translate(0, " + (height - padding) + ")")
     .call(xAxis);

  //draw verical line for lowerWhisker
  svg.append("line")
     .attr("x1", xScale(lowerWhisker))
     .attr("x2", xScale(lowerWhisker))
     .attr("y1", midline - 15)
     .attr("y2", midline + 15);

  //draw vertical line for upperWhisker
  svg.append("line")
     .attr("x1", xScale(upperWhisker))
     .attr("x2", xScale(upperWhisker))
     .attr("y1", midline - 15)
     .attr("y2", midline + 15);

  //draw horizontal line from lowerWhisker to upperWhisker
  svg.append("line")
     .attr("x1",  xScale(lowerWhisker))
     .attr("x2",  xScale(upperWhisker))
     .attr("y1", midline)
     .attr("y2", midline);

  //draw rect for iqr
  svg.append("rect")
     .attr("x", xScale(q1Val))
     .attr("y", padding-5)
     .attr("width", xScale(iqr) - padding)
     .attr("height", 30);

  //draw vertical line at median
  svg.append("line")
     .attr("x1", xScale(medianVal))
     .attr("x2", xScale(medianVal))
     .attr("y1", midline - 15)
     .attr("y2", midline + 15);

  //draw data as points
  svg.append("g")
     .selectAll("circle")
     .data(csv)     
     .enter()
     .append("circle")
     //double point size for outliers
     .attr("r", function(d) {
      if (d.value < lowerWhisker || d.value > upperWhisker)
        return 4;
      else 
        return 2;
     })
     .attr("class", function(d) {
      return "year" + parseDate(d.date).getFullYear();
     })     
     .attr("cy", function(d) { // jitter the points to reduce overplotting
      return random_jitter();
     }) 
     .attr("cx", function(d) {
      return xScale(d.value);   
     })
     //add linked highlighting to interval on point mouseover
     .on("mouseover", function(d) {
        d3.selectAll(".year"+parseDate(d.date).getFullYear())
          .attr("class", "selected");
        d3.select("#interval"+parseDate(d.date).getFullYear())
          .attr("class", "selectedInterval");
     })
     .on("mouseout", function(d) {
        d3.selectAll(".selected")
          .attr("class", "year"+parseDate(d.date).getFullYear());
        d3.selectAll(".selectedInterval")
          .attr("class", "none"); 
     })
     //add tooltip on hover
     .append("title")
     .text(function(d) {
      return "Date: " + d.date + "; value: " + d.value;
     });

});

//add random jitter to points around midline
function random_jitter() {
  if (Math.round(Math.random() * 1) == 0)
    var seed = -5;
  else
    var seed = 5; 
  return midline + Math.floor((Math.random() * seed) + 1);
}

function type(d) {
  d.value = +d.value; // coerce to number
  d.date = d.date;
  return d;
}

data.csv

index.html

<!DOCTYPE html>
<link rel = "stylesheet" type="text/css" href="style.css" />
<style type="text/css"></style>
<html>
	<body>
		<script type="text/javascript" src="http://d3js.org/d3.v3.min.js"></script>
		<script type="text/javascript" src="brushboxplot.js"></script>			
	</body>
</html>

License.txt

This is free and unencumbered software released into the public domain.

Anyone is free to copy, modify, publish, use, compile, sell, or
distribute this software, either in source code form or as a compiled
binary, for any purpose, commercial or non-commercial, and by any
means.

In jurisdictions that recognize copyright laws, the author or authors
of this software dedicate any and all copyright interest in the
software to the public domain. We make this dedication for the benefit
of the public at large and to the detriment of our heirs and
successors. We intend this dedication to be an overt act of
relinquishment in perpetuity of all present and future rights to this
software under copyright law.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.

For more information, please refer to <http://unlicense.org>

style.css

body {
  font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
}

line {
  fill: #fff;
  stroke: #000;
  stroke-width: 1px;
  shape-rendering: crispEdges;
}

rect {
  fill: #fff;
  stroke: #000;
  stroke-width: 1px;
  shape-rendering: crispEdges;
}

circle {
  opacity: 0.2;
  stroke: none;
  shape-rendering: crispEdges;
}

circle:hover {
  stroke: red;
  fill: red;
  opacity: 1;
  stroke-width: 2px;
}

.selected {
  stroke: red;
  fill: red;
  opacity: 1;
  stroke-width: 2px;
}

.axis path {
    fill: none;
    stroke: black;
    stroke-width: 1px;
    shape-rendering: crispEdges;
}

.axis line {
    fill: none;
    stroke: black;
    stroke-width: 1px;
    shape-rendering: crispEdges;
}

.axis text {    
    font-size: 10px;
    -moz-user-select: -moz-none;
    -khtml-user-select: none;
    -webkit-user-select: none;
    -ms-user-select: none;
    user-select: none;
    cursor: default;
}

.selectedInterval {
  stroke: red;
  fill: #E8E8E8;
}

.intervalCell:hover rect {
  stroke: red;
  fill: #EEEEEE;
}

.intervalCell:hover text {
  fill: red;
}

.intervalLabel {
  -moz-user-select: -moz-none;
  -khtml-user-select: none;
  -webkit-user-select: none;
  -ms-user-select: none;
  user-select: none;
  cursor: default;
}

thumbnail.png