Quicksort IV

An improved quicksort animation showing the active partition in black and the active pivot in red.

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

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

.line--pivot {
  stroke: #f00;
  stroke-width: 2.5px;
}

.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)),
    actions = quicksort(array.slice()).reverse();

var margin = {top: 230, right: 40, bottom: 230, left: 40},
    width = 960 - margin.left - margin.right,
    height = 500 - 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").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 + ")");

var line = svg.append("g")
    .attr("class", "line")
  .selectAll("line")
    .data(array)
  .enter().append("line")
    .attr("transform", transform)
    .attr("y2", -height);

function transform(d, i) {
  return "translate(" + x(i) + "," + height + ")rotate(" + a(d) + ")";
}

function quicksort(array) {
  var actions = [];

function partition(left, right, pivot) {
    var v = array[pivot];
    swap(pivot, --right);
    for (var i = left; i < right; ++i) if (array[i] <= v) swap(i, left++);
    swap(left, right);
    return left;
  }

function swap(i, j) {
    if (i === j) return;
    var t = array[i];
    array[i] = array[j];
    array[j] = t;
    actions.push({type: "swap", "0": i, "1": j});
  }

recurse(0, array.length);
  return actions;
}

</script>

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