From 9101efa9f75b47fc04b98c127ce8bd98321d5eb0 Mon Sep 17 00:00:00 2001
From: ben-burlingham <ben.burlingham@boostctr.com>
Date: Sun, 20 Sep 2015 06:50:35 -0700
Subject: [PATCH] Quicksort implementation in place.

---
 index.html | 173 ++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 166 insertions(+), 7 deletions(-)
diff --git a/index.html b/index.html
index 8d0ca52..7ec1c55 100644
--- a/index.html
+++ b/index.html
@@ -5,17 +5,176 @@
     <title>D3</title>
 
     <script type='text/javascript' src='vendor/d3/d3.min.js'></script>
-    <style type='text/css'></style>
+    <style type='text/css'>
+        html, body {
+            margin:0;
+        }
+
+        .quicksort-random {
+            display:block;
+            height:60px;
+            margin:0 auto;
+            width:1198px;
+        }
+    </style>
 </head>
 <body>
     <script type='text/javascript'>
-        var dataset = [ 5, 10, 15, 20, 25 ];
+        var swatchH = 50;
+        var swatchW = 10;
+        var dataset = [];
+
+        // TODO namespace this
+        (function populate() {
+            var len = 100;
+            var r, g, b;
+            for (var i = 0; i < len; i++) {
+                dataset.push({
+                    x: 0,
+                    y: 20,
+                    r: 0, //Math.floor((len - i) * 255 / len),
+                    g: 0,
+                    b: Math.floor(i * 255 / len)
+                });
+            };
+        }());
+
+        dataset = shuffle(dataset);
+
+        var svg = d3.select('body').append('svg')
+            .attr('class', 'quicksort-random');
+
+        var rectangles = svg.selectAll('rect')
+            .data(dataset).enter()
+            .append('rect')
+                .attr('height', swatchH)
+                .attr('width', swatchW)
+                // .attr('')
+                .attr('fill', function fill(d) {
+                    return `rgb(${d.r}, ${d.g}, ${d.b})`;
+                })
+                .attr('y', function y(d) { return d.y; })
+                .attr('x', function x(d) { return d.x; })
+            .transition(500)
+                .attr('x', function xb(d, i) {
+                    dataset[i].x = i * (swatchW + 2);
+                    return dataset[i].x;
+                });
+
+        function visualSwap(indexA, indexB) {
+            // Move up
+            // NOTE Two way binding here between dataset and function parameter
+            rectangles
+                .transition()
+                    .duration(100)
+                    .attr('y', function ya(d, i) {
+                        if (i === indexA || i === indexB) {
+                            dataset[i].y = 5;
+                        }
+
+                        return dataset[i].y;    // NOTE d[i].y has been modified too. But, the bound value in the dataset
+                                                // will not be updated until after the chain is completed, so it has to be explicitly defined here.
+                    })
+
+                // Switch places
+                // NOTE discuss chained transitions: http://bl.ocks.org/mbostock/1125997
+                .transition()
+                    .duration(500)
+                    .attr('x', function xa(d, i) {
+                        if (i === indexA) {
+                            var tmp = dataset[indexA].x;
+                            dataset[indexA].x = dataset[indexB].x;
+                            dataset[indexB].x = tmp;
+                        }
+
+                        return d.x;
+                    })
+
+                // Move down
+                .transition()
+                    .duration(100)
+                    .attr('y', function ya(d, i) {
+                        if (i === indexA || i === indexB) {
+                            dataset[i].y = 20;
+                        }
+
+                        return dataset[i].y;
+                    })
+        };
+
+        function highlight(index) {
+            svg.selectAll('rect')
+                .attr('stroke', function(d, i) { if (i === index) { return 'lime'; } })
+                .attr('stroke-width', function(d, i) { if (i === index) { return 4; } });
+        };
+
+        function unhighlightAll(index) {
+            svg.selectAll('rect')
+                .attr('stroke', function(d, i) { return null; })
+                .attr('stroke-width', function(d, i) { return null; });
+        };
+
+        // NOTE fisher-yates, http://bost.ocks.org/mike/algorithms/
+        function shuffle(arr) {
+            var n = arr.length, t, i;
+            while (n) {
+                i = Math.random() * n-- | 0; // 0 ≤ i < n
+                t = arr[n];
+                arr[n] = arr[i];
+                arr[i] = t;
+            }
+            return arr;
+        };
+
+        // visualSwap(0, 1);
+
+        function quicksort(arr, startIndex, endIndex) {
+            if (endIndex - startIndex <= 0) {
+                return;
+            }
+
+            var left = startIndex;
+            var right = endIndex;
+
+            unhighlightAll();
+            var pivotIndex = Math.floor((right + left) / 2);
+            var pval = arr[pivotIndex].b;
+            var tmp;
+            highlight(pivotIndex);
+
+            while (left <= right) {
+                while (arr[left].b < pval) {
+                    left++;
+                }
+
+                while (arr[right].b > pval) {
+                    right--;
+                }
+
+                if (left <= right) {
+                    tmp = arr[left];
+                    arr[left] = arr[right];
+                    arr[right] = tmp;
+                    visualSwap(left, right);
+
+                    left++;
+                    right--;
+                }
+            }
+
+            quicksort(arr, startIndex, right);
+            quicksort(arr, left, endIndex);
+        };
+
+        quicksort(dataset, 0, dataset.length - 1);
+        console.error(dataset);
+
+        //     var instructions = [];
+        //     instructions.push('M ' + (50 * i) + ',50');
+        //     instructions.push('A 50,50 0 0,1 ' + (50 * (i + 1)) + ',0');
+        //     instructions.push('L ' + (50 * (i + 1)) + ',50');
+        //     instructions.push('L ' + (50 * i) + ',50');
 
-        d3.select("body").selectAll("p")
-            .data(dataset)
-            .enter()
-            .append("p")
-            .text(function(d) { return d; });
     </script>
 </body>
 </html>
