From: Dan Vanderkam <danvdk@gmail.com>
Date: Thu, 29 Aug 2013 20:34:26 +0000 (-0400)
Subject: Merge branch 'release-1.0.1'
X-Git-Tag: v1.1.0~94
X-Git-Url: https://adrianiainlam.tk/git/?a=commitdiff_plain;h=3b3b39e7140cf45dfdc95f636978c5353e3a6c38;hp=c8e018631f692f84d90e827465a0046d33c7836e;p=dygraphs.git

Merge branch 'release-1.0.1'
---

diff --git a/auto_tests/tests/error_bars.js b/auto_tests/tests/error_bars.js
index 1e9d0f4..1c3894c 100644
--- a/auto_tests/tests/error_bars.js
+++ b/auto_tests/tests/error_bars.js
@@ -135,8 +135,8 @@ errorBarsTestCase.prototype.testErrorBarsCorrectColors = function() {
 // Regression test for http://code.google.com/p/dygraphs/issues/detail?id=392
 errorBarsTestCase.prototype.testRollingAveragePreservesNaNs = function() {
   var graph = document.getElementById("graph");
-  var g = new Dygraph(graph,
-  [
+  var data = 
+    [
       [1, [null, null], [3,1]],
       [2, [2, 1], [null, null]],
       [3, [null, null], [5,1]],
@@ -145,8 +145,9 @@ errorBarsTestCase.prototype.testRollingAveragePreservesNaNs = function() {
       [6, [NaN, NaN], [null, null]],
       [8, [8, 1], [null, null]],
       [10, [10, 1], [null, null]]
-     ]
-        , {
+    ];
+  var g = new Dygraph(graph, data,
+        {
           labels: ['x', 'A', 'B' ],
           connectSeparatedPoints: true,
           drawPoints: true,
@@ -154,26 +155,20 @@ errorBarsTestCase.prototype.testRollingAveragePreservesNaNs = function() {
         }
       );
 
-  var in_series = [
-    [1, [null, null]],
-    [2, [2, 1]],
-    [3, [null, null]],
-    [4, [4, 0.5]],
-    [5, [null, null]],
-    [6, [NaN, NaN]],
-    [8, [8, 1]],
-    [10, [10, 1]]
-  ];
-  assertEquals(null, in_series[4][1][0]);
-  assertEquals(null, in_series[4][1][1]);
-  assertNaN(in_series[5][1][0]);
-  assertNaN(in_series[5][1][1]);
-
-  var out_series = g.rollingAverage(in_series, 1);
-  assertNaN(out_series[5][1][0]);
-  assertNaN(out_series[5][1][1]);
-  assertNaN(out_series[5][1][2]);
-  assertEquals(null, out_series[4][1][0]);
-  assertEquals(null, out_series[4][1][1]);
-  assertEquals(null, out_series[4][1][1]);
+  var in_series = g.dataHandler_.extractSeries(data, 1, g.attributes_);
+
+  assertEquals(null, in_series[4][1]);
+  assertEquals(null, in_series[4][2][0]);
+  assertEquals(null, in_series[4][2][1]);
+  assertNaN(in_series[5][1]);
+  assertNaN(in_series[5][2][0]);
+  assertNaN(in_series[5][2][1]);
+
+  var out_series = g.dataHandler_.rollingAverage(in_series, 1, g.attributes_);
+  assertNaN(out_series[5][1]);
+  assertNaN(out_series[5][2][0]);
+  assertNaN(out_series[5][2][1]);
+  assertEquals(null, out_series[4][1]);
+  assertEquals(null, out_series[4][2][0]);
+  assertEquals(null, out_series[4][2][1]);
 };
diff --git a/auto_tests/tests/rolling_average.js b/auto_tests/tests/rolling_average.js
index c0af8f9..86b3e3c 100644
--- a/auto_tests/tests/rolling_average.js
+++ b/auto_tests/tests/rolling_average.js
@@ -87,16 +87,150 @@ rollingAverageTestCase.prototype.testRollShortFractions = function() {
     customBars: true,
     labels: ['x', 'A']
   };
-  var data1 = [ [1, [1, 10, 20]] ];
-  var data2 = [ [1, [1, 10, 20]],
-                [2, [1, 20, 30]],
+  var data1 = [ [1, 10, [1, 20]] ];
+  var data2 = [ [1, 10, [1, 20]],
+                [2, 20, [1, 30]],
               ];
 
   var graph = document.getElementById("graph");
-  var g = new Dygraph(graph, data1, opts);
+  var g = new Dygraph(graph, data2, opts);
 
-  var rolled1 = g.rollingAverage(data1, 1);
-  var rolled2 = g.rollingAverage(data2, 1);
+  var rolled1 = g.dataHandler_.rollingAverage(data1, 1, g);
+  var rolled2 = g.dataHandler_.rollingAverage(data2, 1, g);
 
   assertEquals(rolled1[0], rolled2[0]);
 };
+
+rollingAverageTestCase.prototype.testRollCustomBars = function() {
+  var opts = {
+    customBars: true,
+    rollPeriod: 2,
+    labels: ['x', 'A']
+  };
+  var data = [ [1, [1, 10, 20]],
+               [2, [1, 20, 30]],
+               [3, [1, 30, 40]],
+               [4, [1, 40, 50]]
+              ];
+
+  var graph = document.getElementById("graph");
+  var g = new Dygraph(graph, data, opts);
+  var rolled = this.getRolledData(g, data, 1, 2);
+  assertEquals([1, 10, [1, 20]], rolled[0]);
+  assertEquals([2, 15, [1, 25]], rolled[1]);
+  assertEquals([3, 25, [1, 35]], rolled[2]);
+  assertEquals([4, 35, [1, 45]], rolled[3]);
+};
+
+rollingAverageTestCase.prototype.testRollErrorBars = function() {
+  var opts = {
+    errorBars: true,
+    rollPeriod: 2,
+    labels: ['x', 'A']
+  };
+  var data = [ [1, [10, 1]],
+               [2, [20, 1]],
+               [3, [30, 1]],
+               [4, [40, 1]]
+              ];
+
+  var graph = document.getElementById("graph");
+  var g = new Dygraph(graph, data, opts);
+  var rolled = this.getRolledData(g, data, 1, 2);
+  assertEquals([1, 10, [8, 12]], rolled[0]);
+ 
+  // variance = sqrt( pow(error) * rollPeriod)
+  var variance = Math.sqrt(2);
+  for (var i=1;i<data.length;i++) {
+    var value = data[i][1][0] - 5;
+    assertEquals("unexpected rolled average", value, rolled[i][1]);
+    assertEquals("unexpected rolled min", value - variance, rolled[i][2][0]);
+    assertEquals("unexpected rolled max", value + variance, rolled[i][2][1]);
+  }
+};
+
+rollingAverageTestCase.prototype.testRollFractions = function() {
+  var opts = {
+    fractions: true,
+    rollPeriod: 2,
+    labels: ['x', 'A']
+  };
+  var data = [ [1, [1, 10]],
+               [2, [2, 10]],
+               [3, [3, 10]],
+               [4, [4, 10]]
+              ];
+
+  var graph = document.getElementById("graph");
+  var g = new Dygraph(graph, data, opts);
+  var rolled = this.getRolledData(g, data, 1, 2);
+  assertEquals([1, 10], rolled[0]);
+  assertEquals([2, 15], rolled[1]);
+  assertEquals([3, 25], rolled[2]);
+  assertEquals([4, 35], rolled[3]);
+};
+
+rollingAverageTestCase.prototype.testRollFractionsBars = function() {
+  var opts = {
+    fractions: true,
+    errorBars: true,
+    wilsonInterval: false,
+    rollPeriod: 2,
+    labels: ['x', 'A']
+  };
+  var data = [ [1, [1, 10]],
+               [2, [2, 10]],
+               [3, [3, 10]],
+               [4, [4, 10]]
+              ];
+
+  var graph = document.getElementById("graph");
+  var g = new Dygraph(graph, data, opts);
+  var rolled = this.getRolledData(g, data, 1, 2);
+
+  // precalculated rounded values expected
+  var values = [10, 15, 25, 35];
+  var lows = [-9, -1, 6, 14];
+  var highs = [29, 31, 44, 56];
+
+  for (var i=0;i<data.length;i++) {
+    assertEquals("unexpected rolled average", values[i], Math.round(rolled[i][1]));
+    assertEquals("unexpected rolled min", lows[i], Math.round(rolled[i][2][0]));
+    assertEquals("unexpected rolled max", highs[i], Math.round(rolled[i][2][1]));
+  }
+};
+
+rollingAverageTestCase.prototype.testRollFractionsBarsWilson = function() {
+  var opts = {
+    fractions: true,
+    errorBars: true,
+    wilsonInterval: true,
+    rollPeriod: 2,
+    labels: ['x', 'A']
+  };
+  var data = [ [1, [1, 10]],
+               [2, [2, 10]],
+               [3, [3, 10]],
+               [4, [4, 10]]
+              ];
+
+  var graph = document.getElementById("graph");
+  var g = new Dygraph(graph, data, opts);
+  var rolled = this.getRolledData(g, data, 1, 2);
+
+  //precalculated rounded values expected
+  var values = [10, 15, 25, 35];
+  var lows = [2, 5, 11, 18];
+  var highs = [41, 37, 47, 57];
+
+  for (var i=0;i<data.length;i++) {
+    assertEquals("unexpected rolled average", values[i], Math.round(rolled[i][1]));
+    assertEquals("unexpected rolled min", lows[i], Math.round(rolled[i][2][0]));
+    assertEquals("unexpected rolled max", highs[i], Math.round(rolled[i][2][1]));
+  }
+};
+
+rollingAverageTestCase.prototype.getRolledData = function(g, data, seriesIdx, rollPeriod){
+  var options = g.attributes_;
+  return g.dataHandler_.rollingAverage(g.dataHandler_.extractSeries(data, seriesIdx, options), rollPeriod, options);
+};
diff --git a/closure-todo.txt b/closure-todo.txt
index 392ede4..ae77622 100644
--- a/closure-todo.txt
+++ b/closure-todo.txt
@@ -30,6 +30,15 @@ Plugins:
 - plugins/legend.js
 - plugins/range-selector.js
 
+Datahandler:
+- datahandler/bars-custom.js
+- datahandler/bars-error.js
+- datahandler/bars-fractions.js
+- datahandler/bars.js
+- datahandler/datahandler.js
+- datahandler/default-fractions.js
+- datahandler/default.js
+
 Here's a command that can be used to build dygraphs using the closure
 compiler:
 java -jar ../../closure-compiler-read-only/build/compiler.jar --js=dygraph-utils.js --js=dashed-canvas.js --js=dygraph-options-reference.js --js=dygraph-tickers.js --js=dygraph-gviz.js --js=dygraph-options.js --js_output_file=/tmp/out.js --compilation_level ADVANCED_OPTIMIZATIONS --warning_level VERBOSE --externs dygraph-externs.js
diff --git a/datahandler/bars-custom.js b/datahandler/bars-custom.js
new file mode 100644
index 0000000..37255e5
--- /dev/null
+++ b/datahandler/bars-custom.js
@@ -0,0 +1,96 @@
+/**
+ * @license
+ * Copyright 2013 David Eberlein (david.eberlein@ch.sauter-bc.com)
+ * MIT-licensed (http://opensource.org/licenses/MIT)
+ */
+
+/**
+ * @fileoverview DataHandler implementation for the custom bars option.
+ * @author David Eberlein (david.eberlein@ch.sauter-bc.com)
+ */
+
+(function() {
+
+/*global Dygraph:false */
+"use strict";
+
+Dygraph.DataHandlers.CustomBarsHandler = Dygraph.DataHandler();
+var CustomBarsHandler = Dygraph.DataHandlers.CustomBarsHandler;
+CustomBarsHandler.prototype = new Dygraph.DataHandlers.BarsHandler();
+
+// customBars
+CustomBarsHandler.prototype.extractSeries = function(rawData, i, options) {
+  // TODO(danvk): pre-allocate series here.
+  var series = [];
+  var x, y, point;
+  var logScale = options.get('logscale');
+  for ( var j = 0; j < rawData.length; j++) {
+    x = rawData[j][0];
+    point = rawData[j][i];
+    if (logScale && point !== null) {
+      // On the log scale, points less than zero do not exist.
+      // This will create a gap in the chart.
+      if (point[0] <= 0 || point[1] <= 0 || point[2] <= 0) {
+        point = null;
+      }
+    }
+    // Extract to the unified data format.
+    if (point !== null) {
+      y = point[1];
+      if (y !== null && !isNaN(y)) {
+        series.push([ x, y, [ point[0], point[2] ] ]);
+      } else {
+        series.push([ x, y, [ y, y ] ]);
+      }
+    } else {
+      series.push([ x, null, [ null, null ] ]);
+    }
+  }
+  return series;
+};
+
+CustomBarsHandler.prototype.rollingAverage = function(originalData, rollPeriod,
+    options) {
+  rollPeriod = Math.min(rollPeriod, originalData.length);
+  var rollingData = [];
+  var y, low, high, mid,count, i, extremes;
+
+  low = 0;
+  mid = 0;
+  high = 0;
+  count = 0;
+  for (i = 0; i < originalData.length; i++) {
+    y = originalData[i][1];
+    extremes = originalData[i][2];
+    rollingData[i] = originalData[i];
+
+    if (y !== null && !isNaN(y)) {
+      low += extremes[0];
+      mid += y;
+      high += extremes[1];
+      count += 1;
+    }
+    if (i - rollPeriod >= 0) {
+      var prev = originalData[i - rollPeriod];
+      if (prev[1] !== null && !isNaN(prev[1])) {
+        low -= prev[2][0];
+        mid -= prev[1];
+        high -= prev[2][1];
+        count -= 1;
+      }
+    }
+    if (count) {
+      rollingData[i] = [
+          originalData[i][0],
+          1.0 * mid / count, 
+          [ 1.0 * low / count,
+            1.0 * high / count ] ];
+    } else {
+      rollingData[i] = [ originalData[i][0], null, [ null, null ] ];
+    }
+  }
+
+  return rollingData;
+};
+
+})();
diff --git a/datahandler/bars-error.js b/datahandler/bars-error.js
new file mode 100644
index 0000000..6da2fc5
--- /dev/null
+++ b/datahandler/bars-error.js
@@ -0,0 +1,95 @@
+/**
+ * @license
+ * Copyright 2013 David Eberlein (david.eberlein@ch.sauter-bc.com)
+ * MIT-licensed (http://opensource.org/licenses/MIT)
+ */
+
+/**
+ * @fileoverview DataHandler implementation for the error bars option.
+ * @author David Eberlein (david.eberlein@ch.sauter-bc.com)
+ */
+
+(function() {
+
+/*global Dygraph:false */
+"use strict";
+
+Dygraph.DataHandlers.ErrorBarsHandler = Dygraph.DataHandler();
+var ErrorBarsHandler = Dygraph.DataHandlers.ErrorBarsHandler;
+ErrorBarsHandler.prototype = new Dygraph.DataHandlers.BarsHandler();
+
+// errorBars
+ErrorBarsHandler.prototype.extractSeries = function(rawData, i, options) {
+  // TODO(danvk): pre-allocate series here.
+  var series = [];
+  var x, y, variance, point;
+  var sigma = options.get("sigma");
+  var logScale = options.get('logscale');
+  for ( var j = 0; j < rawData.length; j++) {
+    x = rawData[j][0];
+    point = rawData[j][i];
+    if (logScale && point !== null) {
+      // On the log scale, points less than zero do not exist.
+      // This will create a gap in the chart.
+      if (point[0] <= 0 || point[0] - sigma * point[1] <= 0) {
+        point = null;
+      }
+    }
+    // Extract to the unified data format.
+    if (point !== null) {
+      y = point[0];
+      if (y !== null && !isNaN(y)) {
+        variance = sigma * point[1];
+        // preserve original error value in extras for further
+        // filtering
+        series.push([ x, y, [ y - variance, y + variance, point[1] ] ]);
+      } else {
+        series.push([ x, y, [ y, y, y ] ]);
+      }
+    } else {
+      series.push([ x, null, [ null, null, null ] ]);
+    }
+  }
+  return series;
+};
+
+ErrorBarsHandler.prototype.rollingAverage = function(originalData, rollPeriod,
+    options) {
+  rollPeriod = Math.min(rollPeriod, originalData.length);
+  var rollingData = [];
+  var sigma = options.get("sigma");
+
+  var i, j, y, v, sum, num_ok, stddev, variance, value;
+
+  // Calculate the rolling average for the first rollPeriod - 1 points
+  // where there is not enough data to roll over the full number of points
+  for (i = 0; i < originalData.length; i++) {
+    sum = 0;
+    variance = 0;
+    num_ok = 0;
+    for (j = Math.max(0, i - rollPeriod + 1); j < i + 1; j++) {
+      y = originalData[j][1];
+      if (y === null || isNaN(y))
+        continue;
+      num_ok++;
+      sum += y;
+      variance += Math.pow(originalData[j][2][2], 2);
+    }
+    if (num_ok) {
+      stddev = Math.sqrt(variance) / num_ok;
+      value = sum / num_ok;
+      rollingData[i] = [ originalData[i][0], value,
+          [value - sigma * stddev, value + sigma * stddev] ];
+    } else {
+      // This explicitly preserves NaNs to aid with "independent
+      // series".
+      // See testRollingAveragePreservesNaNs.
+      v = (rollPeriod == 1) ? originalData[i][1] : null;
+      rollingData[i] = [ originalData[i][0], v, [ v, v ] ];
+    }
+  }
+
+  return rollingData;
+};
+
+})();
diff --git a/datahandler/bars-fractions.js b/datahandler/bars-fractions.js
new file mode 100644
index 0000000..28c0491
--- /dev/null
+++ b/datahandler/bars-fractions.js
@@ -0,0 +1,106 @@
+/**
+ * @license
+ * Copyright 2013 David Eberlein (david.eberlein@ch.sauter-bc.com)
+ * MIT-licensed (http://opensource.org/licenses/MIT)
+ */
+
+/**
+ * @fileoverview DataHandler implementation for the combination 
+ * of error bars and fractions options.
+ * @author David Eberlein (david.eberlein@ch.sauter-bc.com)
+ */
+
+(function() {
+
+/*global Dygraph:false */
+"use strict";
+
+Dygraph.DataHandlers.FractionsBarsHandler = Dygraph.DataHandler();
+var FractionsBarsHandler = Dygraph.DataHandlers.FractionsBarsHandler;
+FractionsBarsHandler.prototype = new Dygraph.DataHandlers.BarsHandler();
+
+// errorBars
+FractionsBarsHandler.prototype.extractSeries = function(rawData, i, options) {
+  // TODO(danvk): pre-allocate series here.
+  var series = [];
+  var x, y, point, num, den, value, stddev, variance;
+  var mult = 100.0;
+  var sigma = options.get("sigma");
+  var logScale = options.get('logscale');
+  for ( var j = 0; j < rawData.length; j++) {
+    x = rawData[j][0];
+    point = rawData[j][i];
+    if (logScale && point !== null) {
+      // On the log scale, points less than zero do not exist.
+      // This will create a gap in the chart.
+      if (point[0] <= 0 || point[1] <= 0) {
+        point = null;
+      }
+    }
+    // Extract to the unified data format.
+    if (point !== null) {
+      num = point[0];
+      den = point[1];
+      if (num !== null && !isNaN(num)) {
+        value = den ? num / den : 0.0;
+        stddev = den ? sigma * Math.sqrt(value * (1 - value) / den) : 1.0;
+        variance = mult * stddev;
+        y = mult * value;
+        // preserve original values in extras for further filtering
+        series.push([ x, y, [ y - variance, y + variance, num, den ] ]);
+      } else {
+        series.push([ x, num, [ num, num, num, den ] ]);
+      }
+    } else {
+      series.push([ x, null, [ null, null, null, null ] ]);
+    }
+  }
+  return series;
+};
+
+FractionsBarsHandler.prototype.rollingAverage = function(originalData, rollPeriod,
+    options) {
+  rollPeriod = Math.min(rollPeriod, originalData.length);
+  var rollingData = [];
+  var sigma = options.get("sigma");
+  var wilsonInterval = options.get("wilsonInterval");
+
+  var low, high, i, stddev;
+  var num = 0;
+  var den = 0; // numerator/denominator
+  var mult = 100.0;
+  for (i = 0; i < originalData.length; i++) {
+    num += originalData[i][2][2];
+    den += originalData[i][2][3];
+    if (i - rollPeriod >= 0) {
+      num -= originalData[i - rollPeriod][2][2];
+      den -= originalData[i - rollPeriod][2][3];
+    }
+
+    var date = originalData[i][0];
+    var value = den ? num / den : 0.0;
+    if (wilsonInterval) {
+      // For more details on this confidence interval, see:
+      // http://en.wikipedia.org/wiki/Binomial_confidence_interval
+      if (den) {
+        var p = value < 0 ? 0 : value, n = den;
+        var pm = sigma * Math.sqrt(p * (1 - p) / n + sigma * sigma / (4 * n * n));
+        var denom = 1 + sigma * sigma / den;
+        low = (p + sigma * sigma / (2 * den) - pm) / denom;
+        high = (p + sigma * sigma / (2 * den) + pm) / denom;
+        rollingData[i] = [ date, p * mult,
+            [ low * mult, high * mult ] ];
+      } else {
+        rollingData[i] = [ date, 0, [ 0, 0 ] ];
+      }
+    } else {
+      stddev = den ? sigma * Math.sqrt(value * (1 - value) / den) : 1.0;
+      rollingData[i] = [ date, mult * value, 
+                         [ mult * (value - stddev), mult * (value + stddev) ] ];
+    }
+  }
+
+  return rollingData;
+};
+
+})();
diff --git a/datahandler/bars.js b/datahandler/bars.js
new file mode 100644
index 0000000..914ee27
--- /dev/null
+++ b/datahandler/bars.js
@@ -0,0 +1,77 @@
+/**
+ * @license
+ * Copyright 2013 David Eberlein (david.eberlein@ch.sauter-bc.com)
+ * MIT-licensed (http://opensource.org/licenses/MIT)
+ */
+
+/**
+ * @fileoverview DataHandler base implementation for the "bar" 
+ * data formats. This implementation must be extended and the
+ * extractSeries and rollingAverage must be implemented.
+ * @author David Eberlein (david.eberlein@ch.sauter-bc.com)
+ */
+
+(function() {
+
+/*global Dygraph:false */
+/*global DygraphLayout:false */
+"use strict";
+
+Dygraph.DataHandlers.BarsHandler = Dygraph.DataHandler();
+var BarsHandler = Dygraph.DataHandlers.BarsHandler;
+
+// errorBars
+BarsHandler.prototype.extractSeries = function(rawData, i, options) {
+  // Not implemented here must be extended
+};
+
+BarsHandler.prototype.rollingAverage =
+    function(originalData, rollPeriod, options) {
+  // Not implemented here, must be extended.
+};
+
+BarsHandler.prototype.onPointsCreated_ = function(series, points) {
+  for (var i = 0; i < series.length; ++i) {
+    var item = series[i];
+    var point = points[i];
+    point.y_top = NaN;
+    point.y_bottom = NaN;
+    point.yval_minus = DygraphLayout.parseFloat_(item[2][0]);
+    point.yval_plus = DygraphLayout.parseFloat_(item[2][1]);
+  }
+};
+
+BarsHandler.prototype.getExtremeYValues = function(series, dateWindow, options) {
+  var minY = null, maxY = null, y;
+
+  var firstIdx = 0;
+  var lastIdx = series.length - 1;
+
+  for ( var j = firstIdx; j <= lastIdx; j++) {
+    y = series[j][1];
+    if (y === null || isNaN(y)) continue;
+
+    var low = series[j][2][0];
+    var high = series[j][2][1];
+
+    if (low > y) low = y; // this can happen with custom bars,
+    if (high < y) high = y; // e.g. in tests/custom-bars.html
+
+    if (maxY === null || high > maxY) maxY = high;
+    if (minY === null || low < minY) minY = low;
+  }
+
+  return [ minY, maxY ];
+};
+
+BarsHandler.prototype.onLineEvaluated = function(points, axis, logscale) {
+  var point;
+  for (var j = 0; j < points.length; j++) {
+    // Copy over the error terms
+    point = points[j];
+    point.y_top = DygraphLayout._calcYNormal(axis, point.yval_minus, logscale);
+    point.y_bottom = DygraphLayout._calcYNormal(axis, point.yval_plus, logscale);
+  }
+};
+
+})();
diff --git a/datahandler/datahandler.js b/datahandler/datahandler.js
new file mode 100644
index 0000000..5ed0112
--- /dev/null
+++ b/datahandler/datahandler.js
@@ -0,0 +1,263 @@
+/**
+ * @license
+ * Copyright 2013 David Eberlein (david.eberlein@ch.sauter-bc.com)
+ * MIT-licensed (http://opensource.org/licenses/MIT)
+ */
+
+/**
+ * @fileoverview This file contains the managment of data handlers
+ * @author David Eberlein (david.eberlein@ch.sauter-bc.com)
+ * 
+ * The idea is to define a common, generic data format that works for all data
+ * structures supported by dygraphs. To make this possible, the DataHandler
+ * interface is introduced. This makes it possible, that dygraph itself can work
+ * with the same logic for every data type independent of the actual format and
+ * the DataHandler takes care of the data format specific jobs. 
+ * DataHandlers are implemented for all data types supported by Dygraphs and
+ * return Dygraphs compliant formats.
+ * By default the correct DataHandler is chosen based on the options set.
+ * Optionally the user may use his own DataHandler (similar to the plugin
+ * system).
+ * 
+ * 
+ * The unified data format returend by each handler is defined as so: 
+ * series[n][point] = [x,y,(extras)] 
+ * 
+ * This format contains the common basis that is needed to draw a simple line
+ * series extended by optional extras for more complex graphing types. It
+ * contains a primitive x value as first array entry, a primitive y value as
+ * second array entry and an optional extras object for additional data needed.
+ * 
+ * x must always be a number.
+ * y must always be a number, NaN of type number or null.
+ * extras is optional and must be interpreted by the DataHandler. It may be of
+ * any type. 
+ * 
+ * In practice this might look something like this:
+ * default: [x, yVal]
+ * errorBar / customBar: [x, yVal, [yTopVariance, yBottomVariance] ]
+ * 
+ */
+/*global Dygraph:false */
+/*global DygraphLayout:false */
+
+(function() {
+
+"use strict";
+
+/**
+ * A collection of functions to create and retrieve data handlers.
+ * @type {Object.<!Dygraph.DataHandler>}
+ */
+Dygraph.DataHandlers = {};
+
+/**
+ * 
+ * The data handler is responsible for all data specific operations. All of the
+ * series data it receives and returns is always in the unified data format.
+ * Initially the unified data is created by the extractSeries method
+ */
+Dygraph.DataHandler = function () {
+  /**
+   * Constructor for all data handlers.
+   * @constructor
+   */
+  var handler = function() {
+    return this;
+  };
+
+  /**
+   * X-value array index constant for unified data samples.
+   * @const
+   * @type {number}
+   */
+  handler.X = 0;
+
+  /**
+   * Y-value array index constant for unified data samples.
+   * @const
+   * @type {number}
+   */
+  handler.Y = 1;
+
+  /**
+   * Extras-value array index constant for unified data samples.
+   * @const
+   * @type {number}
+   */
+  handler.EXTRAS = 2;
+
+  /**
+   * Extracts one series from the raw data (a 2D array) into an array of the
+   * unified data format.
+   * This is where undesirable points (i.e. negative values on log scales and
+   * missing values through which we wish to connect lines) are dropped.
+   * TODO(danvk): the "missing values" bit above doesn't seem right.
+   * 
+   * @param rawData {!Array.<Array>} The raw data passed into dygraphs where 
+   *          rawData[i] = [x,ySeries1,...,ySeriesN].
+   * @param seriesIndex {!number} Index of the series to extract. All other series should
+   *          be ignored.
+   * @param options {!DygraphOptions} Dygraph options.
+   * @returns {Array.<[!number,?number,?]>} The series in the unified data format
+   *          where series[i] = [x,y,{extras}]. 
+   * @public
+   */
+  handler.prototype.extractSeries = function(rawData, seriesIndex, options) {
+  };
+
+  /**
+   * Converts a series to a Point array.
+   * 
+   * @param {!Array.<[!number,?number,?]>} series The series in the unified 
+   *          data format where series[i] = [x,y,{extras}].
+   * @param {!string} setName Name of the series.
+   * @param {!number} boundaryIdStart Index offset of the first point, equal to the
+   *          number of skipped points left of the date window minimum (if any).
+   * @return {!Array.<Dygraph.PointType>} List of points for this series.
+   * @public
+   */
+  handler.prototype.seriesToPoints = function(series, setName, boundaryIdStart) {
+    // TODO(bhs): these loops are a hot-spot for high-point-count charts. In
+    // fact,
+    // on chrome+linux, they are 6 times more expensive than iterating through
+    // the
+    // points and drawing the lines. The brunt of the cost comes from allocating
+    // the |point| structures.
+    var points = [];
+    for ( var i = 0; i < series.length; ++i) {
+      var item = series[i];
+      var yraw = item[1];
+      var yval = yraw === null ? null : DygraphLayout.parseFloat_(yraw);
+      var point = {
+        x : NaN,
+        y : NaN,
+        xval : DygraphLayout.parseFloat_(item[0]),
+        yval : yval,
+        name : setName, // TODO(danvk): is this really necessary?
+        idx : i + boundaryIdStart
+      };
+      points.push(point);
+    }
+    handler.prototype.onPointsCreated_(series, points);
+    return points;
+  };
+
+  /**
+   * Callback called for each series after the series points have been generated
+   * which will later be used by the plotters to draw the graph.
+   * Here data may be added to the seriesPoints which is needed by the plotters.
+   * The indexes of series and points are in sync meaning the original data
+   * sample for series[i] is points[i].
+   * 
+   * @param {!Array.<[!number,?number,?]>} series The series in the unified 
+   *          data format where series[i] = [x,y,{extras}].
+   * @param {!Array.<Dygraph.PointType>} points The corresponding points passed 
+   *          to the plotter.
+   * @private
+   */
+  handler.prototype.onPointsCreated_ = function(series, points) {
+  };
+
+  /**
+   * Calculates the rolling average of a data set.
+   * 
+   * @param {!Array.<[!number,?number,?]>} series The series in the unified 
+   *          data format where series[i] = [x,y,{extras}].
+   * @param {!number} rollPeriod The number of points over which to average the data
+   * @param {!DygraphOptions} options The dygraph options.
+   * @return the rolled series.
+   * @public
+   */
+  handler.prototype.rollingAverage = function(series, rollPeriod, options) {
+  };
+
+  /**
+   * Computes the range of the data series (including confidence intervals).
+   * 
+   * @param {!Array.<[!number,?number,?]>} series The series in the unified 
+   *          data format where series[i] = [x,y,{extras}].
+   * @param {!Array.<number>} dateWindow The x-value range to display with 
+   *          the format: [min,max].
+   * @param {!DygraphOptions} options The dygraph options.
+   * @return {Array.<number>} The low and high extremes of the series in the given window with 
+   *          the format: [low, high].
+   * @public
+   */
+  handler.prototype.getExtremeYValues = function(series, dateWindow, options) {
+  };
+
+  /**
+   * Callback called for each series after the layouting data has been
+   * calculated before the series is drawn. Here normalized positioning data
+   * should be calculated for the extras of each point.
+   * 
+   * @param {!Array.<Dygraph.PointType>} points The points passed to 
+   *          the plotter.
+   * @param {!Object} axis The axis on which the series will be plotted.
+   * @param {!boolean} logscale Weather or not to use a logscale.
+   * @public
+   */
+  handler.prototype.onLineEvaluated = function(points, axis, logscale) {
+  };
+
+  /**
+   * Helper method that computes the y value of a line defined by the points p1
+   * and p2 and a given x value.
+   * 
+   * @param {!Array.<number>} p1 left point ([x,y]).
+   * @param {!Array.<number>} p2 right point ([x,y]).
+   * @param {!number} xValue The x value to compute the y-intersection for.
+   * @return {number} corresponding y value to x on the line defined by p1 and p2.
+   * @private
+   */
+  handler.prototype.computeYInterpolation_ = function(p1, p2, xValue) {
+    var deltaY = p2[1] - p1[1];
+    var deltaX = p2[0] - p1[0];
+    var gradient = deltaY / deltaX;
+    var growth = (xValue - p1[0]) * gradient;
+    return p1[1] + growth;
+  };
+
+  /**
+   * Helper method that returns the first and the last index of the given series
+   * that lie inside the given dateWindow.
+   * 
+   * @param {!Array.<[!number,?number,?]>} series The series in the unified 
+   *          data format where series[i] = [x,y,{extras}].
+   * @param {!Array.<number>} dateWindow The x-value range to display with 
+   *          the format: [min,max].
+   * @return {!Array.<[!number,?number,?]>} The samples of the series that 
+   *          are in the given date window.
+   * @private
+   */
+  handler.prototype.getIndexesInWindow_ = function(series, dateWindow) {
+    var firstIdx = 0, lastIdx = series.length - 1;
+    if (dateWindow) {
+      var idx = 0;
+      var low = dateWindow[0];
+      var high = dateWindow[1];
+
+      // Start from each side of the array to minimize the performance
+      // needed.
+      while (idx < series.length - 1 && series[idx][0] < low) {
+        firstIdx++;
+        idx++;
+      }
+      idx = series.length - 1;
+      while (idx > 0 && series[idx][0] > high) {
+        lastIdx--;
+        idx--;
+      }
+    }
+    if (firstIdx <= lastIdx) {
+      return [ firstIdx, lastIdx ];
+    } else {
+      return [ 0, series.length - 1 ];
+    }
+  };
+
+  return handler;
+};
+
+})();
diff --git a/datahandler/default-fractions.js b/datahandler/default-fractions.js
new file mode 100644
index 0000000..8da8e42
--- /dev/null
+++ b/datahandler/default-fractions.js
@@ -0,0 +1,81 @@
+/**
+ * @license
+ * Copyright 2013 David Eberlein (david.eberlein@ch.sauter-bc.com)
+ * MIT-licensed (http://opensource.org/licenses/MIT)
+ */
+
+/**
+ * @fileoverview DataHandler implementation for the fractions option.
+ * @author David Eberlein (david.eberlein@ch.sauter-bc.com)
+ */
+
+(function() {
+
+/*global Dygraph:false */
+"use strict";
+
+Dygraph.DataHandlers.DefaultFractionHandler = Dygraph.DataHandler();
+var DefaultFractionHandler = Dygraph.DataHandlers.DefaultFractionHandler;
+DefaultFractionHandler.prototype = new Dygraph.DataHandlers.DefaultHandler();
+
+DefaultFractionHandler.prototype.extractSeries = function(rawData, i, options) {
+  // TODO(danvk): pre-allocate series here.
+  var series = [];
+  var x, y, point, num, den, value;
+  var mult = 100.0;
+  var logScale = options.get('logscale');
+  for ( var j = 0; j < rawData.length; j++) {
+    x = rawData[j][0];
+    point = rawData[j][i];
+    if (logScale && point !== null) {
+      // On the log scale, points less than zero do not exist.
+      // This will create a gap in the chart.
+      if (point[0] <= 0 || point[1] <= 0) {
+        point = null;
+      }
+    }
+    // Extract to the unified data format.
+    if (point !== null) {
+      num = point[0];
+      den = point[1];
+      if (num !== null && !isNaN(num)) {
+        value = den ? num / den : 0.0;
+        y = mult * value;
+        // preserve original values in extras for further filtering
+        series.push([ x, y, [ num, den ] ]);
+      } else {
+        series.push([ x, num, [ num, den ] ]);
+      }
+    } else {
+      series.push([ x, null, [ null, null ] ]);
+    }
+  }
+  return series;
+};
+
+DefaultFractionHandler.prototype.rollingAverage = function(originalData, rollPeriod,
+    options) {
+  rollPeriod = Math.min(rollPeriod, originalData.length);
+  var rollingData = [];
+
+  var i;
+  var num = 0;
+  var den = 0; // numerator/denominator
+  var mult = 100.0;
+  for (i = 0; i < originalData.length; i++) {
+    num += originalData[i][2][0];
+    den += originalData[i][2][1];
+    if (i - rollPeriod >= 0) {
+      num -= originalData[i - rollPeriod][2][0];
+      den -= originalData[i - rollPeriod][2][1];
+    }
+
+    var date = originalData[i][0];
+    var value = den ? num / den : 0.0;
+    rollingData[i] = [ date, mult * value ];
+  }
+
+  return rollingData;
+};
+
+})();
diff --git a/datahandler/default.js b/datahandler/default.js
new file mode 100644
index 0000000..6e6697f
--- /dev/null
+++ b/datahandler/default.js
@@ -0,0 +1,90 @@
+/**
+ * @license
+ * Copyright 2013 David Eberlein (david.eberlein@ch.sauter-bc.com)
+ * MIT-licensed (http://opensource.org/licenses/MIT)
+ */
+
+/**
+ * @fileoverview DataHandler default implementation used for simple line charts.
+ * @author David Eberlein (david.eberlein@ch.sauter-bc.com)
+ */
+
+(function() {
+
+/*global Dygraph:false */
+"use strict";
+
+Dygraph.DataHandlers.DefaultHandler = Dygraph.DataHandler();
+var DefaultHandler = Dygraph.DataHandlers.DefaultHandler;
+
+DefaultHandler.prototype.extractSeries = function(rawData, i, options) {
+  // TODO(danvk): pre-allocate series here.
+  var series = [];
+  var logScale = options.get('logscale');
+  for ( var j = 0; j < rawData.length; j++) {
+    var x = rawData[j][0];
+    var point = rawData[j][i];
+    if (logScale) {
+      // On the log scale, points less than zero do not exist.
+      // This will create a gap in the chart.
+      if (point <= 0) {
+        point = null;
+      }
+    }
+    series.push([ x, point ]);
+  }
+  return series;
+};
+
+DefaultHandler.prototype.rollingAverage = function(originalData, rollPeriod,
+    options) {
+  rollPeriod = Math.min(rollPeriod, originalData.length);
+  var rollingData = [];
+
+  var i, j, y, sum, num_ok;
+  // Calculate the rolling average for the first rollPeriod - 1 points
+  // where
+  // there is not enough data to roll over the full number of points
+  if (rollPeriod == 1) {
+    return originalData;
+  }
+  for (i = 0; i < originalData.length; i++) {
+    sum = 0;
+    num_ok = 0;
+    for (j = Math.max(0, i - rollPeriod + 1); j < i + 1; j++) {
+      y = originalData[j][1];
+      if (y === null || isNaN(y))
+        continue;
+      num_ok++;
+      sum += originalData[j][1];
+    }
+    if (num_ok) {
+      rollingData[i] = [ originalData[i][0], sum / num_ok ];
+    } else {
+      rollingData[i] = [ originalData[i][0], null ];
+    }
+  }
+
+  return rollingData;
+};
+
+DefaultHandler.prototype.getExtremeYValues = function(series, dateWindow,
+    options) {
+  var minY = null, maxY = null, y;
+  var firstIdx = 0, lastIdx = series.length - 1;
+
+  for ( var j = firstIdx; j <= lastIdx; j++) {
+    y = series[j][1];
+    if (y === null || isNaN(y))
+      continue;
+    if (maxY === null || y > maxY) {
+      maxY = y;
+    }
+    if (minY === null || y < minY) {
+      minY = y;
+    }
+  }
+  return [ minY, maxY ];
+};
+
+})();
diff --git a/dygraph-dev.js b/dygraph-dev.js
index c06d23d..160a01e 100644
--- a/dygraph-dev.js
+++ b/dygraph-dev.js
@@ -36,7 +36,14 @@
     "plugins/legend.js",
     "plugins/range-selector.js",
     "dygraph-plugin-install.js",
-    "dygraph-options-reference.js"  // Shouldn't be included in generate-combined.sh
+    "dygraph-options-reference.js",  // Shouldn't be included in generate-combined.sh
+    "datahandler/datahandler.js",
+    "datahandler/default.js",
+    "datahandler/default-fractions.js",
+    "datahandler/bars.js",
+    "datahandler/bars-error.js",
+    "datahandler/bars-custom.js",
+    "datahandler/bars-fractions.js"
   ];
 
   for (var i = 0; i < source_files.length; i++) {
diff --git a/dygraph-layout.js b/dygraph-layout.js
index e766e8f..93e0c3a 100644
--- a/dygraph-layout.js
+++ b/dygraph-layout.js
@@ -222,7 +222,6 @@ DygraphLayout._calcYNormal = function(axis, value, logscale) {
 DygraphLayout.prototype._evaluateLineCharts = function() {
   var connectSeparated = this.attr_('connectSeparatedPoints');
   var isStacked = this.attr_("stackedGraph");
-  var hasBars = this.attr_('errorBars') || this.attr_('customBars');
 
   for (var setIdx = 0; setIdx < this.points.length; setIdx++) {
     var points = this.points[setIdx];
@@ -252,14 +251,9 @@ DygraphLayout.prototype._evaluateLineCharts = function() {
         }
       }
       point.y = DygraphLayout._calcYNormal(axis, yval, logscale);
-
-      if (hasBars) {
-        point.y_top = DygraphLayout._calcYNormal(
-            axis, yval - point.yval_minus, logscale);
-        point.y_bottom = DygraphLayout._calcYNormal(
-            axis, yval + point.yval_plus, logscale);
-      }
     }
+
+    this.dygraph_.dataHandler_.onLineEvaluated(points, axis, logscale);
   }
 };
 
diff --git a/dygraph-options-reference.js b/dygraph-options-reference.js
index c952072..6220750 100644
--- a/dygraph-options-reference.js
+++ b/dygraph-options-reference.js
@@ -802,7 +802,13 @@ Dygraph.OPTIONS_REFERENCE =  // <JSON>
     "default": "[]",
     "labels": ["Configuration"],
     "type": "Array<plugin>",
-    "description": "Defines per-graph plug-ins. Useful for per-graph customization"
+    "description": "Defines per-graph plugins. Useful for per-graph customization"
+  },
+  "dataHandler": {
+    "default": "(depends on data)",
+    "labels": ["Data"],
+    "type": "Dygraph.DataHandler",
+    "description": "Custom DataHandler. This is an advanced customization. See http://bit.ly/151E7Aq."
   }
 }
 ;  // </JSON>
diff --git a/dygraph.js b/dygraph.js
index 1d33570..effe10d 100644
--- a/dygraph.js
+++ b/dygraph.js
@@ -2153,46 +2153,27 @@ Dygraph.prototype.addXTicks_ = function() {
 };
 
 /**
+ * Returns the correct handler class for the currently set options.
  * @private
- * Computes the range of the data series (including confidence intervals).
- * @param { [Array] } series either [ [x1, y1], [x2, y2], ... ] or
- * [ [x1, [y1, dev_low, dev_high]], [x2, [y2, dev_low, dev_high]], ...
- * @return [low, high]
- */
-Dygraph.prototype.extremeValues_ = function(series) {
-  var minY = null, maxY = null, j, y;
-
-  var bars = this.attr_("errorBars") || this.attr_("customBars");
-  if (bars) {
-    // With custom bars, maxY is the max of the high values.
-    for (j = 0; j < series.length; j++) {
-      y = series[j][1][0];
-      if (y === null || isNaN(y)) continue;
-      var low = y - series[j][1][1];
-      var high = y + series[j][1][2];
-      if (low > y) low = y;    // this can happen with custom bars,
-      if (high < y) high = y;  // e.g. in tests/custom-bars.html
-      if (maxY === null || high > maxY) {
-        maxY = high;
-      }
-      if (minY === null || low < minY) {
-        minY = low;
-      }
+ */
+Dygraph.prototype.getHandlerClass_ = function() {
+  var handlerClass;
+  if (this.attr_('dataHandler')) {
+    handlerClass =  this.attr_('dataHandler');
+  } else if (this.fractions_) {
+    if (this.attr_('errorBars')) {
+      handlerClass = Dygraph.DataHandlers.FractionsBarsHandler;
+    } else {
+      handlerClass = Dygraph.DataHandlers.DefaultFractionHandler;
     }
+  } else if (this.attr_('customBars')) {
+    handlerClass = Dygraph.DataHandlers.CustomBarsHandler;
+  } else if (this.attr_('errorBars')) {
+    handlerClass = Dygraph.DataHandlers.ErrorBarsHandler;
   } else {
-    for (j = 0; j < series.length; j++) {
-      y = series[j][1];
-      if (y === null || isNaN(y)) continue;
-      if (maxY === null || y > maxY) {
-        maxY = y;
-      }
-      if (minY === null || y < minY) {
-        minY = y;
-      }
-    }
+    handlerClass = Dygraph.DataHandlers.DefaultHandler;
   }
-
-  return [minY, maxY];
+  return handlerClass;
 };
 
 /**
@@ -2205,6 +2186,9 @@ Dygraph.prototype.extremeValues_ = function(series) {
  */
 Dygraph.prototype.predraw_ = function() {
   var start = new Date();
+  
+  // Create the correct dataHandler
+  this.dataHandler_ = new (this.getHandlerClass_())();
 
   this.layout_.computePlotArea();
 
@@ -2241,9 +2225,11 @@ Dygraph.prototype.predraw_ = function() {
   this.rolledSeries_ = [null];  // x-axis is the first series and it's special
   for (var i = 1; i < this.numColumns(); i++) {
     // var logScale = this.attr_('logscale', i); // TODO(klausw): this looks wrong // konigsberg thinks so too.
-    var logScale = this.attr_('logscale');
-    var series = this.extractSeries_(this.rawData_, i, logScale);
-    series = this.rollingAverage(series, this.rollPeriod_);
+    var series = this.dataHandler_.extractSeries(this.rawData_, i, this.attributes_);
+    if (this.rollPeriod_ > 1) {
+      series = this.dataHandler_.rollingAverage(series, this.rollPeriod_, this.attributes_);
+    }
+    
     this.rolledSeries_.push(series);
   }
 
@@ -2280,49 +2266,6 @@ Dygraph.prototype.predraw_ = function() {
  */
 Dygraph.PointType = undefined;
 
-// TODO(bhs): these loops are a hot-spot for high-point-count charts. In fact,
-// on chrome+linux, they are 6 times more expensive than iterating through the
-// points and drawing the lines. The brunt of the cost comes from allocating
-// the |point| structures.
-/**
- * Converts a series to a Point array.
- *
- * @private
- * @param {Array.<Array.<(?number|Array<?number>)>} series Array where
- *     series[row] = [x,y] or [x, [y, err]] or [x, [y, yplus, yminus]].
- * @param {boolean} bars True if error bars or custom bars are being drawn.
- * @param {string} setName Name of the series.
- * @param {number} boundaryIdStart Index offset of the first point, equal to
- *     the number of skipped points left of the date window minimum (if any).
- * @return {Array.<Dygraph.PointType>} List of points for this series.
- */
-Dygraph.seriesToPoints_ = function(series, bars, setName, boundaryIdStart) {
-  var points = [];
-  for (var i = 0; i < series.length; ++i) {
-    var item = series[i];
-    var yraw = bars ? item[1][0] : item[1];
-    var yval = yraw === null ? null : DygraphLayout.parseFloat_(yraw);
-    var point = {
-      x: NaN,
-      y: NaN,
-      xval: DygraphLayout.parseFloat_(item[0]),
-      yval: yval,
-      name: setName,  // TODO(danvk): is this really necessary?
-      idx: i + boundaryIdStart
-    };
-
-    if (bars) {
-      point.y_top = NaN;
-      point.y_bottom = NaN;
-      point.yval_minus = DygraphLayout.parseFloat_(item[1][1]);
-      point.yval_plus = DygraphLayout.parseFloat_(item[1][2]);
-    }
-    points.push(point);
-  }
-  return points;
-};
-
-
 /**
  * Calculates point stacking for stackedGraph=true.
  *
@@ -2438,43 +2381,34 @@ Dygraph.prototype.gatherDatasets_ = function(rolledSeries, dateWindow) {
   var points = [];
   var cumulativeYval = [];  // For stacked series.
   var extremes = {};  // series name -> [low, high]
-  var i, k;
-  var errorBars = this.attr_("errorBars");
-  var customBars = this.attr_("customBars");
-  var bars = errorBars || customBars;
-  var isValueNull = function(sample) {
-    if (!bars) {
-      return sample[1] === null;
-    } else {
-      return customBars ? sample[1][1] === null : 
-        errorBars ? sample[1][0] === null : false;
-    }
-  };
-
+  var seriesIdx, sampleIdx;
+  var firstIdx, lastIdx;
+  
   // Loop over the fields (series).  Go from the last to the first,
   // because if they're stacked that's how we accumulate the values.
   var num_series = rolledSeries.length - 1;
   var series;
-  for (i = num_series; i >= 1; i--) {
-    if (!this.visibility()[i - 1]) continue;
+  for (seriesIdx = num_series; seriesIdx >= 1; seriesIdx--) {
+    if (!this.visibility()[seriesIdx - 1]) continue;
 
     // Prune down to the desired range, if necessary (for zooming)
     // Because there can be lines going to points outside of the visible area,
     // we actually prune to visible points, plus one on either side.
     if (dateWindow) {
-      series = rolledSeries[i];
+      series = rolledSeries[seriesIdx];
       var low = dateWindow[0];
       var high = dateWindow[1];
 
       // TODO(danvk): do binary search instead of linear search.
       // TODO(danvk): pass firstIdx and lastIdx directly to the renderer.
-      var firstIdx = null, lastIdx = null;
-      for (k = 0; k < series.length; k++) {
-        if (series[k][0] >= low && firstIdx === null) {
-          firstIdx = k;
+      firstIdx = null; 
+      lastIdx = null;
+      for (sampleIdx = 0; sampleIdx < series.length; sampleIdx++) {
+        if (series[sampleIdx][0] >= low && firstIdx === null) {
+          firstIdx = sampleIdx;
         }
-        if (series[k][0] <= high) {
-          lastIdx = k;
+        if (series[sampleIdx][0] <= high) {
+          lastIdx = sampleIdx;
         }
       }
 
@@ -2483,7 +2417,8 @@ Dygraph.prototype.gatherDatasets_ = function(rolledSeries, dateWindow) {
       var isInvalidValue = true;
       while (isInvalidValue && correctedFirstIdx > 0) {
         correctedFirstIdx--;
-        isInvalidValue = isValueNull(series[correctedFirstIdx]);
+        // check if the y value is null.
+        isInvalidValue = series[correctedFirstIdx][1] === null;
       }
 
       if (lastIdx === null) lastIdx = series.length - 1;
@@ -2491,10 +2426,9 @@ Dygraph.prototype.gatherDatasets_ = function(rolledSeries, dateWindow) {
       isInvalidValue = true;
       while (isInvalidValue && correctedLastIdx < series.length - 1) {
         correctedLastIdx++;
-        isInvalidValue = isValueNull(series[correctedLastIdx]);
+        isInvalidValue = series[correctedLastIdx][1] === null;
       }
 
-
       if (correctedFirstIdx!==firstIdx) {
         firstIdx = correctedFirstIdx;
       }
@@ -2502,20 +2436,21 @@ Dygraph.prototype.gatherDatasets_ = function(rolledSeries, dateWindow) {
         lastIdx = correctedLastIdx;
       }
       
-      boundaryIds[i-1] = [firstIdx, lastIdx];
+      boundaryIds[seriesIdx-1] = [firstIdx, lastIdx];
       
       // .slice's end is exclusive, we want to include lastIdx.
       series = series.slice(firstIdx, lastIdx + 1);
     } else {
-      series = rolledSeries[i];
-      boundaryIds[i-1] = [0, series.length-1];
+      series = rolledSeries[seriesIdx];
+      boundaryIds[seriesIdx-1] = [0, series.length-1];
     }
 
-    var seriesName = this.attr_("labels")[i];
-    var seriesExtremes = this.extremeValues_(series);
+    var seriesName = this.attr_("labels")[seriesIdx];
+    var seriesExtremes = this.dataHandler_.getExtremeYValues(series, 
+        dateWindow, this.attr_("stepPlot",seriesName));
 
-    var seriesPoints = Dygraph.seriesToPoints_(
-        series, bars, seriesName, boundaryIds[i-1][0]);
+    var seriesPoints = this.dataHandler_.seriesToPoints(series, 
+        seriesName, boundaryIds[seriesIdx-1][0]);
 
     if (this.attr_("stackedGraph")) {
       Dygraph.stackPoints_(seriesPoints, cumulativeYval, seriesExtremes,
@@ -2523,7 +2458,7 @@ Dygraph.prototype.gatherDatasets_ = function(rolledSeries, dateWindow) {
     }
 
     extremes[seriesName] = seriesExtremes;
-    points[i] = seriesPoints;
+    points[seriesIdx] = seriesPoints;
   }
 
   return { points: points, extremes: extremes, boundaryIds: boundaryIds };
@@ -2900,198 +2835,6 @@ Dygraph.prototype.computeYAxisRanges_ = function(extremes) {
 };
 
 /**
- * Extracts one series from the raw data (a 2D array) into an array of (date,
- * value) tuples.
- *
- * This is where undesirable points (i.e. negative values on log scales and
- * missing values through which we wish to connect lines) are dropped.
- * TODO(danvk): the "missing values" bit above doesn't seem right.
- *
- * @private
- * @param {Array.<Array.<(number|Array<Number>)>>} rawData Input data. Rectangular
- *     grid of points, where rawData[row][0] is the X value for the row,
- *     and rawData[row][i] is the Y data for series #i.
- * @param {number} i Series index, starting from 1.
- * @param {boolean} logScale True if using logarithmic Y scale.
- * @return {Array.<Array.<(?number|Array<?number>)>} Series array, where
- *     series[row] = [x,y] or [x, [y, err]] or [x, [y, yplus, yminus]].
- */
-Dygraph.prototype.extractSeries_ = function(rawData, i, logScale) {
-  // TODO(danvk): pre-allocate series here.
-  var series = [];
-  var errorBars = this.attr_("errorBars");
-  var customBars =  this.attr_("customBars");
-  for (var j = 0; j < rawData.length; j++) {
-    var x = rawData[j][0];
-    var point = rawData[j][i];
-    if (logScale) {
-      // On the log scale, points less than zero do not exist.
-      // This will create a gap in the chart.
-      if (errorBars || customBars) {
-        // point.length is either 2 (errorBars) or 3 (customBars)
-        for (var k = 0; k < point.length; k++) {
-          if (point[k] <= 0) {
-            point = null;
-            break;
-          }
-        }
-      } else if (point <= 0) {
-        point = null;
-      }
-    }
-    // Fix null points to fit the display type standard.
-    if (point !== null) {
-      series.push([x, point]);
-    } else {
-      series.push([x, errorBars ? [null, null] : customBars ? [null, null, null] : point]);
-    }
-  }
-  return series;
-};
-
-/**
- * @private
- * Calculates the rolling average of a data set.
- * If originalData is [label, val], rolls the average of those.
- * If originalData is [label, [, it's interpreted as [value, stddev]
- *   and the roll is returned in the same form, with appropriately reduced
- *   stddev for each value.
- * Note that this is where fractional input (i.e. '5/10') is converted into
- *   decimal values.
- * @param {Array} originalData The data in the appropriate format (see above)
- * @param {Number} rollPeriod The number of points over which to average the
- *                            data
- */
-Dygraph.prototype.rollingAverage = function(originalData, rollPeriod) {
-  rollPeriod = Math.min(rollPeriod, originalData.length);
-  var rollingData = [];
-  var sigma = this.attr_("sigma");
-
-  var low, high, i, j, y, sum, num_ok, stddev;
-  if (this.fractions_) {
-    var num = 0;
-    var den = 0;  // numerator/denominator
-    var mult = 100.0;
-    for (i = 0; i < originalData.length; i++) {
-      num += originalData[i][1][0];
-      den += originalData[i][1][1];
-      if (i - rollPeriod >= 0) {
-        num -= originalData[i - rollPeriod][1][0];
-        den -= originalData[i - rollPeriod][1][1];
-      }
-
-      var date = originalData[i][0];
-      var value = den ? num / den : 0.0;
-      if (this.attr_("errorBars")) {
-        if (this.attr_("wilsonInterval")) {
-          // For more details on this confidence interval, see:
-          // http://en.wikipedia.org/wiki/Binomial_confidence_interval
-          if (den) {
-            var p = value < 0 ? 0 : value, n = den;
-            var pm = sigma * Math.sqrt(p*(1-p)/n + sigma*sigma/(4*n*n));
-            var denom = 1 + sigma * sigma / den;
-            low  = (p + sigma * sigma / (2 * den) - pm) / denom;
-            high = (p + sigma * sigma / (2 * den) + pm) / denom;
-            rollingData[i] = [date,
-                              [p * mult, (p - low) * mult, (high - p) * mult]];
-          } else {
-            rollingData[i] = [date, [0, 0, 0]];
-          }
-        } else {
-          stddev = den ? sigma * Math.sqrt(value * (1 - value) / den) : 1.0;
-          rollingData[i] = [date, [mult * value, mult * stddev, mult * stddev]];
-        }
-      } else {
-        rollingData[i] = [date, mult * value];
-      }
-    }
-  } else if (this.attr_("customBars")) {
-    low = 0;
-    var mid = 0;
-    high = 0;
-    var count = 0;
-    for (i = 0; i < originalData.length; i++) {
-      var data = originalData[i][1];
-      y = data[1];
-      rollingData[i] = [originalData[i][0], [y, y - data[0], data[2] - y]];
-
-      if (y !== null && !isNaN(y)) {
-        low += data[0];
-        mid += y;
-        high += data[2];
-        count += 1;
-      }
-      if (i - rollPeriod >= 0) {
-        var prev = originalData[i - rollPeriod];
-        if (prev[1][1] !== null && !isNaN(prev[1][1])) {
-          low -= prev[1][0];
-          mid -= prev[1][1];
-          high -= prev[1][2];
-          count -= 1;
-        }
-      }
-      if (count) {
-        rollingData[i] = [originalData[i][0], [ 1.0 * mid / count,
-                                                1.0 * (mid - low) / count,
-                                                1.0 * (high - mid) / count ]];
-      } else {
-        rollingData[i] = [originalData[i][0], [null, null, null]];
-      }
-    }
-  } else {
-    // Calculate the rolling average for the first rollPeriod - 1 points where
-    // there is not enough data to roll over the full number of points
-    if (!this.attr_("errorBars")) {
-      if (rollPeriod == 1) {
-        return originalData;
-      }
-
-      for (i = 0; i < originalData.length; i++) {
-        sum = 0;
-        num_ok = 0;
-        for (j = Math.max(0, i - rollPeriod + 1); j < i + 1; j++) {
-          y = originalData[j][1];
-          if (y === null || isNaN(y)) continue;
-          num_ok++;
-          sum += originalData[j][1];
-        }
-        if (num_ok) {
-          rollingData[i] = [originalData[i][0], sum / num_ok];
-        } else {
-          rollingData[i] = [originalData[i][0], null];
-        }
-      }
-
-    } else {
-      for (i = 0; i < originalData.length; i++) {
-        sum = 0;
-        var variance = 0;
-        num_ok = 0;
-        for (j = Math.max(0, i - rollPeriod + 1); j < i + 1; j++) {
-          y = originalData[j][1][0];
-          if (y === null || isNaN(y)) continue;
-          num_ok++;
-          sum += originalData[j][1][0];
-          variance += Math.pow(originalData[j][1][1], 2);
-        }
-        if (num_ok) {
-          stddev = Math.sqrt(variance) / num_ok;
-          rollingData[i] = [originalData[i][0],
-                            [sum / num_ok, sigma * stddev, sigma * stddev]];
-        } else {
-          // This explicitly preserves NaNs to aid with "independent series".
-          // See testRollingAveragePreservesNaNs.
-          var v = (rollPeriod == 1) ? originalData[i][1][0] : null;
-          rollingData[i] = [originalData[i][0], [v, v, v]];
-        }
-      }
-    }
-  }
-
-  return rollingData;
-};
-
-/**
  * Detects the type of the str (date or numeric) and sets the various
  * formatting attributes in this.attrs_ based on this type.
  * @param {String} str An x value.
@@ -3886,6 +3629,3 @@ Dygraph.addAnnotationRule = function() {
 
   this.warn("Unable to add default annotation CSS rule; display may be off.");
 };
-
-// Older pages may still use this name.
-var DateGraph = Dygraph;
diff --git a/generate-combined.sh b/generate-combined.sh
index 9e184ae..09f316f 100755
--- a/generate-combined.sh
+++ b/generate-combined.sh
@@ -19,7 +19,14 @@ GetSources () {
     dygraph-tickers.js \
     dygraph-plugin-base.js \
     plugins/*.js \
-    dygraph-plugin-install.js
+    dygraph-plugin-install.js \
+    datahandler/datahandler.js \
+    datahandler/default.js \
+    datahandler/default-fractions.js \
+    datahandler/bars.js \
+    datahandler/bars-custom.js \
+    datahandler/bars-error.js \
+    datahandler/bars-fractions.js 
   do
       echo "$F"
   done
diff --git a/jsTestDriver.conf b/jsTestDriver.conf
index ffbc369..04f49da 100644
--- a/jsTestDriver.conf
+++ b/jsTestDriver.conf
@@ -20,4 +20,11 @@ load:
   - dygraph-plugin-base.js
   - plugins/*.js
   - dygraph-plugin-install.js
+  - datahandler/datahandler.js
+  - datahandler/default.js
+  - datahandler/default-fractions.js
+  - datahandler/bars.js
+  - datahandler/bars-error.js
+  - datahandler/bars-custom.js
+  - datahandler/bars-fractions.js
   - auto_tests/tests/*.js
diff --git a/lint.sh b/lint.sh
index ef4dacd..eb61924 100755
--- a/lint.sh
+++ b/lint.sh
@@ -21,7 +21,7 @@ fi
 RETURN_VALUE=0
 
 if [ $# -eq 0 ]; then
-  files=$(ls dygraph*.js plugins/*.js | grep -v combined | grep -v dev.js| grep -v externs)
+  files=$(ls dygraph*.js plugins/*.js datahandler/*.js | grep -v combined | grep -v dev.js| grep -v externs)
 else
   files=$1
 fi