Mergesort III

A static visualization of mergesort. Each row represents the state of the array after a single pass. The size of the sorted subarrays doubles with each successive pass.

<!DOCTYPE html>
<meta charset="utf-8">
<style>

body {
  padding: 10px 0;
}

svg {
  float: left;
}

.line {
  stroke: #000;
  stroke-width: 1.5px;
  stroke-linecap: round;
}

.line--inactive {
  stroke: #ddd;
  stroke-width: 1px;
}

</style>
<body>
<script src="//d3js.org/d3.v3.min.js"></script>
<script>

var n = 200,
    array = d3.shuffle(d3.range(n)),
    arrays = mergesort(array.slice());

var margin = {top: 6, right: 30, bottom: 6, left: 30},
    width = 960 - margin.left - margin.right,
    height = 50 - margin.top - margin.bottom;

var x = d3.scale.ordinal()
    .domain(d3.range(n))
    .rangePoints([0, width]);

var a = d3.scale.linear()
    .domain([0, n - 1])
    .range([-45, 45]);

var svg = d3.select("body").selectAll("svg")
    .data(arrays)
  .enter().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 + ")");

svg.append("g")
    .attr("class", "line")
  .selectAll("line")
    .data(function(d) { return d; })
  .enter().append("line")
    .attr("transform", function(d, i) { return "translate(" + x(i) + "," + height + ")rotate(" + a(d) + ")"; })
    .attr("y2", -height);

function mergesort(array) {
  var arrays = [array.slice()],
      n = array.length,
      array0 = array,
      array1 = new Array(n);

for (var m = 1; m < n; m <<= 1) {
    for (var i = 0; i < n; i += (m << 1)) {
      merge(i, Math.min(i + m, n), Math.min(i + (m << 1), n));
    }
    arrays.push(array1.slice());
    array = array0, array0 = array1, array1 = array;
  }

function merge(left, right, end) {
    for (var i0 = left, i1 = right, j = left; j < end; ++j) {
      array1[j] = array0[i0 < right && (i1 >= end || array0[i0] <= array0[i1]) ? i0++ : i1++];
    }
  }

return arrays;
}

d3.select(self.frameElement).style("height", (height + margin.top + margin.bottom) * arrays.length + 20 + "px");

</script>

https://d3js.org/d3.v3.min.js