js/source/legacy/SGN/Histogram.js

   1
   2 //Pass an array of values e.g. ['1.01', '2', '500'] and the div_id for the div you want the histogram to appear in.
   3
   4 function plot_histogram(values, div_id) {
   5
   6   var identical = identical_check(values);
   7
   8   if (identical == true) {
   9       jQuery("#"+div_id).html("<center><h3>All "+values.length+" values were the same value of "+values[0]+".</h3></center>");
  10   }  else {
  11
  12       // A formatter for counts.
  13       var formatCount = d3.format(",.0f");
  14
  15       var div_width = document.getElementById(div_id).offsetWidth;
  16
  17       var margin = {top: 10, right: 30, bottom: 30, left: 30},
  18       width = div_width - margin.left - margin.right,
  19       height = 200 - margin.top - margin.bottom;
  20
  21       var x = d3.scale.linear()
  22       .domain([d3.min(values),d3.max(values)])
  23       .range([0, width]);
  24
  25       // Generate a histogram using twenty uniformly-spaced bins.
  26       var data = d3.layout.histogram()
  27       .bins(x.ticks(20))
  28       (values);
  29
  30       var y = d3.scale.linear()
  31       .domain([0, d3.max(data, function(d) { return d.y; })])
  32       .range([height, 0]);
  33
  34       var xAxis = d3.svg.axis()
  35       .scale(x)
  36       .orient("bottom");
  37
  38       var svg = d3.select("#"+div_id).append("svg")
  39       .attr("id", "svg_id")
  40       .attr("width", width + margin.left + margin.right)
  41       .attr("height", height + margin.top + margin.bottom)
  42       .append("g")
  43       .attr("id", "g_id")
  44       .attr("transform", "translate(" + margin.left + "," + margin.top + ")");
  45
  46       var bar = svg.selectAll(".bar")
  47       .data(data)
  48       .enter().append("g")
  49       .attr("id", "g_id")
  50       .attr("class", "bar")
  51       .attr("transform", function(d) { return "translate(" + x(d.x) + "," + y(d.y) + ")"; });
  52
  53       bar.append("rect")
  54       .attr("id", "rect_id")
  55       .attr("x", 1)
  56       .attr("width", (x.range()[1] - x.range()[0]) / 20 )
  57       .attr("height", function(d) { return height - y(d.y); });
  58
  59       bar.append("text")
  60       .attr("id", "text_id")
  61       .attr("dy", ".75em")
  62       .attr("y", 6)
  63       .attr("x", ((x.range()[1] - x.range()[0]) / 20) / 2)
  64       .attr("text-anchor", "middle")
  65       .text(function(d) { return formatCount(d.y); });
  66
  67       svg.append("g")
  68       .attr("id", "g_id")
  69       .attr("class", "x axis")
  70       .attr("transform", "translate(0," + height + ")")
  71       .call(xAxis);
  72
  73   }
  74 }
  75
  76 function identical_check(array) {
  77     for(var i = 0; i < array.length - 1; i++) {
  78         if(array[i] != array[i+1]) {
  79             return false;
  80         }
  81     }
  82     return true;
  83 }