Add repeated transactions

Add flot resize library
Update to more recent flot git repo
Closes #5

.gitmodules

 [submodule "externals/flot"]
 	path = externals/flot
-	url = https://github.com/FooBarWidget/flot.git
+	url = https://github.com/tback/flot.git 
 [submodule "externals/jquery.history"]
 	path = externals/jquery.history
 	url = https://github.com/tkyk/jquery-history-plugin.git

analyser.js

  return this.toFixed(2).replace(/([0-9])(?=([0-9]{3})+\.)/g, '$1,');
 };
 
+/**
+ * Computes the arithmatic mean, variance and deviation for the given array.
+ *
+ * @param a Array of numbers to be averaged
+ * @return A map containing the mean, variance and deviation
+ */
+function getAverage(a){
+ var r = {mean: 0, variance: 0, deviation: 0};
+ var length = a.length;
+
+ // Sum the array
+ for (var sum = 0, i = length; i--; sum += a[i]);
+
+ var mean = r.mean = sum / length
+
+ // Sum the squares of the differences from the mean
+ for (var i = length, sum = 0; i--; sum += Math.pow(a[i] - mean, 2));
+
+ r.deviation = Math.sqrt(r.variance = sum / length)
+ return r;
+}
+
 /**
  * Adds an 'alt' class to every other visible row in the specified table.
  *
  });
 }
 
+/**
+ * Calculates repeat transactions within the specified data.
+ *
+ * @param data The data to be analysed
+ */
+function calculateRepeatTransactions(data) {
+ $('#repeats').show();
+ $('#repeats tr.data').remove();
+ var table = $('#repeats table');
+
+ var descs = {};
+
+ $.each(data, function() {
+  if (!descs[this.Description]) { descs[this.Description] = []; }
+  descs[this.Description].push(this);
+ });
+
+ var monthTotal = 0;
+ $.each(descs, function(desc) {
+  // We only care if there are at least more than 2
+  if (this.length < 3) { return; }
+
+  var lastTime = 0;
+  var differences = [];
+  var amounts = [];
+
+  $.each(this, function() {
+   var time = new Date(this.Date.date).getTime();
+   lastTime > 0 && differences.push(time - lastTime);
+   lastTime = time;
+   amounts.push(this.Amount);
+  });
+
+  var average = getAverage(differences);
+  var averageAmount = getAverage(amounts);
+
+  // I may have just made this metric up. Sue me.
+  var stability = average.deviation / average.mean;
+  var periodInDays = average.mean / (1000 * 60 * 60 * 24);
+
+  if (stability < 0.5) {
+   // Seems quite reliable...
+   if ((periodInDays >= 5 && periodInDays <= 9) || (periodInDays >= 27 && periodInDays <= 32)) {
+    // Roughly weekly or monthly
+    var monthValue = (periodInDays <= 9 ? 4 : 1) * averageAmount.mean;
+
+    var tr = $('<tr class="data"/>').appendTo(table);
+    $('<td/>').text(desc).appendTo(tr);
+    $('<td/>').text(this[0].Category ? this[0].Category : 'Unsorted').appendTo(tr);
+    $('<td/>').text(periodInDays <= 9 ? 'Weekly' : 'Monthly').appendTo(tr);
+    $('<td class="amount"/>').text(averageAmount.mean.toCurrency()).appendTo(tr);
+    $('<td class="amount"/>').text(monthValue.toCurrency()).appendTo(tr);
+
+    monthTotal += monthValue;
+   }
+  }
+ });
+
+ colourTableRows(table);
+ var tr = $('<tr/>').addClass('data total').appendTo(table);
+ $('<th colspan="4" class="total">Total</th>').appendTo(tr);
+ $('<td class="amount"></td>').text(monthTotal.toCurrency()).appendTo(tr);
+}
+
 /**
  * Displays transactions and draws a category pie chart for the specified
  * date range. Note that dates have a granularity of a month.
 
  colourTableRows(table);
  drawCategoryPieChart(included, incoming);
+ calculateRepeatTransactions(included);
 }
 
 $(function() {

externals/flot

-Subproject commit 171538ec32e26a6167d8e43b9722ec2bf612115b
+Subproject commit 6328221ea9d507b2150e59f09d9eb9265e9dc127

index.html

   <script src="externals/flot/jquery.js" type="text/javascript"></script>
   <script src="externals/flot/jquery.flot.js" type="text/javascript"></script>
   <script src="externals/flot/jquery.flot.pie.js" type="text/javascript"></script>
+  <script src="externals/flot/jquery.flot.resize.js" type="text/javascript"></script>
   <script src="externals/flot/jquery.flot.selection.js" type="text/javascript"></script>
   <script src="externals/flot/jquery.flot.stack.js" type="text/javascript"></script>
   <script src="externals/jquery.history/jquery.history.js" type="text/javascript"></script>
    #historytable tr.collapsed { opacity: 0.6; }
    table tr.total td, table tr.total th { background-color: #666; color: #fff; }
    .amount { text-align: right; }
+   .datatable { width: 100%; }
   </style>
  </head>
  <body>
   <div class="left">
    <h2>Transaction History</h2>
    <div id="history" style="width: 100%; height: 300px;" class="graph"></div>
-   <div id="historytable" style="display: none;"><h3>Transactions for ??</h3><table><tr><th>Date</th><th>Type</th><th>Category</th><th>Description</th><th>Amount</th></tr></table></div>
+   <div id="historytable" style="display: none;">
+    <h3>Transactions for ??</h3>
+    <table class="datatable"><tr><th>Date</th><th>Type</th><th>Category</th><th>Description</th><th>Amount</th></tr></table>
+   </div>
   </div>
   <div class="right">
    <h2>Categories</h2>
    <div id="expense" style="width: 100%; height: 300px;" class="graph"></div>
    <h2>Expense Categories</h2>
-   <div id="cathistory" style="width: 100%; height: 600px;" class="graph"></div>
+   <!-- The tick labels on the X-Axis extend a bit beyond the edge of the
+        graph, so make the graph 50px smaller so the page doesn't scroll -->
+   <div style="padding-right: 50px;">
+    <div id="cathistory" style="width: 100%; height: 600px;" class="graph"></div>
+   </div>
+   <div id="repeats" style="display: none;">
+    <h2>Repeat Transactions</h2>
+    <table class="datatable">
+     <tr><th rowspan="2">Transaction</th><th rowspan="2">Category</th><th rowspan="2">Frequency</th><th colspan="2">Average amount</th></tr>
+     <tr><th>Per trans</th><th>Per month</th></tr>
+    </table>
+   </div>
   </div>
  </body>
 </html>