Log scale panning. I'm feeling really good about just how damn well this lined up...

[dygraphs.git] / dygraph.js

diff --git a/dygraph.js b/dygraph.js
index d738e54..8f69337 100644 (file)
--- a/dygraph.js
+++ b/dygraph.js
@@ -24,7 +24,6 @@
 
  If the 'errorBars' option is set in the constructor, the input should be of
  the form
 
  If the 'errorBars' option is set in the constructor, the input should be of
  the form

-

    Date,SeriesA,SeriesB,...
    YYYYMMDD,A1,sigmaA1,B1,sigmaB1,...
    YYYYMMDD,A2,sigmaA2,B2,sigmaB2,...
    Date,SeriesA,SeriesB,...
    YYYYMMDD,A1,sigmaA1,B1,sigmaB1,...
    YYYYMMDD,A2,sigmaA2,B2,sigmaB2,...


@@ -80,9 +79,9 @@ Dygraph.DEFAULT_HEIGHT = 320;
 Dygraph.AXIS_LINE_WIDTH = 0.3;
 
 Dygraph.LOG_SCALE = 10;
 Dygraph.AXIS_LINE_WIDTH = 0.3;
 
 Dygraph.LOG_SCALE = 10;

-Dygraph.LOG_BASE_E_OF_TEN = Math.log(Dygraph.LOG_SCALE);
+Dygraph.LN_TEN = Math.log(Dygraph.LOG_SCALE);

 Dygraph.log10 = function(x) {
 Dygraph.log10 = function(x) {

-  return Math.log(x) / Dygraph.LOG_BASE_E_OF_TEN;
+  return Math.log(x) / Dygraph.LN_TEN;

 }
 
 // Default attribute values.
 }
 
 // Default attribute values.


@@ -119,7 +118,6 @@ Dygraph.DEFAULT_ATTRS = {
 
   delimiter: ',',
 
 
   delimiter: ',',
 

-  logScale: false,

   sigma: 2.0,
   errorBars: false,
   fractions: false,
   sigma: 2.0,
   errorBars: false,
   fractions: false,


@@ -362,7 +360,7 @@ Dygraph.prototype.yAxisRanges = function() {
  * axis. Uses the first axis by default.
  * Returns a two-element array: [X, Y]
  *
  * axis. Uses the first axis by default.
  * Returns a two-element array: [X, Y]
  *

- * Note: use toDomXCoord instead of toDomCoords(x. null) and use toDomYCoord
+ * Note: use toDomXCoord instead of toDomCoords(x, null) and use toDomYCoord

  * instead of toDomCoords(null, y, axis).
  */
 Dygraph.prototype.toDomCoords = function(x, y, axis) {
  * instead of toDomCoords(null, y, axis).
  */
 Dygraph.prototype.toDomCoords = function(x, y, axis) {


@@ -372,8 +370,8 @@ Dygraph.prototype.toDomCoords = function(x, y, axis) {
 /**
  * Convert from data x coordinates to canvas/div X coordinate.
  * If specified, do this conversion for the coordinate system of a particular
 /**
  * Convert from data x coordinates to canvas/div X coordinate.
  * If specified, do this conversion for the coordinate system of a particular

- * axis. Uses the first axis by default.
- * returns a single value or null if x is null.
+ * axis.
+ * Returns a single value or null if x is null.

  */
 Dygraph.prototype.toDomXCoord = function(x) {
   if (x == null) {
  */
 Dygraph.prototype.toDomXCoord = function(x) {
   if (x == null) {


@@ -392,11 +390,12 @@ Dygraph.prototype.toDomXCoord = function(x) {
  * returns a single value or null if y is null.
  */
 Dygraph.prototype.toDomYCoord = function(y, axis) {
  * returns a single value or null if y is null.
  */
 Dygraph.prototype.toDomYCoord = function(y, axis) {

-  var pct = toPercentYCoord(y, axis);
+  var pct = this.toPercentYCoord(y, axis);

 
   if (pct == null) {
     return null;
   }
 
   if (pct == null) {
     return null;
   }

+  var area = this.plotter_.area;

   return area.y + pct * area.h;
 }
 
   return area.y + pct * area.h;
 }
 


@@ -406,7 +405,7 @@ Dygraph.prototype.toDomYCoord = function(y, axis) {
  * axis. Uses the first axis by default.
  * Returns a two-element array: [X, Y].
  *
  * axis. Uses the first axis by default.
  * Returns a two-element array: [X, Y].
  *

- * Note: use toDataXCoord instead of toDataCoords(x. null) and use toDataYCoord
+ * Note: use toDataXCoord instead of toDataCoords(x, null) and use toDataYCoord

  * instead of toDataCoords(null, y, axis).
  */
 Dygraph.prototype.toDataCoords = function(x, y, axis) {
  * instead of toDataCoords(null, y, axis).
  */
 Dygraph.prototype.toDataCoords = function(x, y, axis) {


@@ -442,7 +441,8 @@ Dygraph.prototype.toDataYCoord = function(y, axis) {
   var area = this.plotter_.area;
   var yRange = this.yAxisRange(axis);
 
   var area = this.plotter_.area;
   var yRange = this.yAxisRange(axis);
 

-  if (!this.attr_("logscale")) {
+  if (typeof(axis) == "undefined") axis = 0;
+  if (!this.axes_[axis].logscale) {

     return yRange[0] + (area.h - y) / area.h * (yRange[1] - yRange[0]);
   } else {
     // Computing the inverse of toDomCoord.
     return yRange[0] + (area.h - y) / area.h * (yRange[1] - yRange[0]);
   } else {
     // Computing the inverse of toDomCoord.


@@ -488,12 +488,13 @@ Dygraph.prototype.toPercentYCoord = function(y, axis) {
   if (y == null) {
     return null;
   }
   if (y == null) {
     return null;
   }

+  if (typeof(axis) == "undefined") axis = 0;

 
   var area = this.plotter_.area;
   var yRange = this.yAxisRange(axis);
 
   var pct;
 
   var area = this.plotter_.area;
   var yRange = this.yAxisRange(axis);
 
   var pct;

-  if (!this.attr_("logscale")) {
+  if (!this.axes_[axis].logscale) {

     // yrange[1] - y is unit distance from the bottom.
     // yrange[1] - yrange[0] is the scale of the range.
     // (yRange[1] - y) / (yRange[1] - yRange[0]) is the % from the bottom.
     // yrange[1] - y is unit distance from the bottom.
     // yrange[1] - yrange[0] is the scale of the range.
     // (yRange[1] - y) / (yRange[1] - yRange[0]) is the % from the bottom.


@@ -911,6 +912,8 @@ Dygraph.startPan = function(event, g, context) {
   context.isPanning = true;
   var xRange = g.xAxisRange();
   context.dateRange = xRange[1] - xRange[0];
   context.isPanning = true;
   var xRange = g.xAxisRange();
   context.dateRange = xRange[1] - xRange[0];

+  context.initialLeftmostDate = xRange[0];
+  context.xUnitsPerPixel = context.dateRange / (g.plotter_.area.w - 1);

 
   // Record the range of each y-axis at the start of the drag.
   // If any axis has a valueRange or valueWindow, then we want a 2D pan.
 
   // Record the range of each y-axis at the start of the drag.
   // If any axis has a valueRange or valueWindow, then we want a 2D pan.


@@ -918,14 +921,20 @@ Dygraph.startPan = function(event, g, context) {
   for (var i = 0; i < g.axes_.length; i++) {
     var axis = g.axes_[i];
     var yRange = g.yAxisRange(i);
   for (var i = 0; i < g.axes_.length; i++) {
     var axis = g.axes_[i];
     var yRange = g.yAxisRange(i);

-    axis.dragValueRange = yRange[1] - yRange[0];
-    axis.draggingValue = g.toDataYCoord(context.dragStartY, i);
+    // TODO(konigsberg): These values should be in |context|.
+    // In log scale, initialTopValue, dragValueRange and unitsPerPixel are log scale.
+    if (axis.logscale) {
+      axis.initialTopValue = Dygraph.log10(yRange[1]);
+      axis.dragValueRange = Dygraph.log10(yRange[1]) - Dygraph.log10(yRange[0]);
+    } else {
+      axis.initialTopValue = yRange[1];
+      axis.dragValueRange = yRange[1] - yRange[0];
+    }
+    axis.unitsPerPixel = axis.dragValueRange / (g.plotter_.area.h - 1);
+
+    // While calculating axes, set 2dpan.

     if (axis.valueWindow || axis.valueRange) context.is2DPan = true;
   }
     if (axis.valueWindow || axis.valueRange) context.is2DPan = true;
   }

-
-  // TODO(konigsberg): Switch from all this math to toDataCoords?
-  // Seems to work for the dragging value.
-  context.draggingDate = (context.dragStartX / g.width_) * context.dateRange + xRange[0];

 };
 
 // Called in response to an interaction model operation that
 };
 
 // Called in response to an interaction model operation that


@@ -939,33 +948,28 @@ Dygraph.movePan = function(event, g, context) {
   context.dragEndX = g.dragGetX_(event, context);
   context.dragEndY = g.dragGetY_(event, context);
 
   context.dragEndX = g.dragGetX_(event, context);
   context.dragEndY = g.dragGetY_(event, context);
 

-  // TODO(danvk): update this comment
-  // Want to have it so that:
-  // 1. draggingDate appears at dragEndX, draggingValue appears at dragEndY.
-  // 2. daterange = (dateWindow_[1] - dateWindow_[0]) is unaltered.
-  // 3. draggingValue appears at dragEndY.
-  // 4. valueRange is unaltered.
-
-  var minDate = context.draggingDate - (context.dragEndX / g.width_) * context.dateRange;
+  var minDate = context.initialLeftmostDate -
+    (context.dragEndX - context.dragStartX) * context.xUnitsPerPixel;

   var maxDate = minDate + context.dateRange;
   g.dateWindow_ = [minDate, maxDate];
 
   // y-axis scaling is automatic unless this is a full 2D pan.
   if (context.is2DPan) {
     // Adjust each axis appropriately.
   var maxDate = minDate + context.dateRange;
   g.dateWindow_ = [minDate, maxDate];
 
   // y-axis scaling is automatic unless this is a full 2D pan.
   if (context.is2DPan) {
     // Adjust each axis appropriately.

-    // NOTE(konigsberg): I don't think this computation for y_frac is correct.
-    // I think it doesn't take into account the display of the x axis.
-    // See, when I tested this with console.log(y_frac), and move the mouse
-    // cursor to the botom, the largest y_frac was 0.94, and not 1.0. That
-    // could also explain why panning tends to start with a small jumpy shift.
-    var y_frac = context.dragEndY / g.height_;
-

     for (var i = 0; i < g.axes_.length; i++) {
       var axis = g.axes_[i];
     for (var i = 0; i < g.axes_.length; i++) {
       var axis = g.axes_[i];

-      var maxValue = axis.draggingValue + y_frac * axis.dragValueRange;
+
+      var pixelsDragged = context.dragEndY - context.dragStartY;
+      var unitsDragged = pixelsDragged * axis.unitsPerPixel;
+
+      // In log scale, maxValue and minValue are the logs of those values.
+      var maxValue = axis.initialTopValue + unitsDragged;

       var minValue = maxValue - axis.dragValueRange;
       var minValue = maxValue - axis.dragValueRange;

-      console.log(axis.draggingValue, axis.dragValueRange, minValue, maxValue, y_frac);
-      axis.valueWindow = [ minValue, maxValue ];
+      if (axis.logscale) {
+        axis.valueWindow = [ Math.pow(10, minValue), Math.pow(10, maxValue) ];
+      } else {
+        axis.valueWindow = [ minValue, maxValue ];
+      }

     }
   }
 
     }
   }
 


@@ -980,9 +984,12 @@ Dygraph.movePan = function(event, g, context) {
 // panning behavior.
 //
 Dygraph.endPan = function(event, g, context) {
 // panning behavior.
 //
 Dygraph.endPan = function(event, g, context) {

+  // TODO(konigsberg): Clear the context data from the axis.
+  // TODO(konigsberg): mouseup should just delete the
+  // context object, and mousedown should create a new one.

   context.isPanning = false;
   context.is2DPan = false;
   context.isPanning = false;
   context.is2DPan = false;

-  context.draggingDate = null;
+  context.initialLeftmostDate = null;

   context.dateRange = null;
   context.valueRange = null;
 }
   context.dateRange = null;
   context.valueRange = null;
 }


@@ -1158,12 +1165,12 @@ Dygraph.prototype.createDragInterface_ = function() {
     prevEndY: null,
     prevDragDirection: null,
 
     prevEndY: null,
     prevDragDirection: null,
 

-    // TODO(danvk): update this comment
-    // draggingDate and draggingValue represent the [date,value] point on the
-    // graph at which the mouse was pressed. As the mouse moves while panning,
-    // the viewport must pan so that the mouse position points to
-    // [draggingDate, draggingValue]
-    draggingDate: null,
+    // The value on the left side of the graph when a pan operation starts.
+    initialLeftmostDate: null,
+
+    // The number of units each pixel spans. (This won't be valid for log
+    // scales)
+    xUnitsPerPixel: null,

 
     // TODO(danvk): update this comment
     // The range in second/value units that the viewport encompasses during a
 
     // TODO(danvk): update this comment
     // The range in second/value units that the viewport encompasses during a


@@ -1914,12 +1921,71 @@ Dygraph.dateTicker = function(startDate, endDate, self) {
   }
 };
 
   }
 };
 

+Dygraph.PREFERRED_LOG_TICK_VALUES = function() {
+  var vals = [];
+  for (var power = -39; power <= 39; power++) {
+    var range = Math.pow(10, power);
+    for (var mult = 1; mult <= 9; mult++) {
+      var val = range * mult;
+      vals.push(val);
+    }
+  }
+  return vals;
+}();
+
+// val is the value to search for
+// arry is the value over which to search
+// if abs > 0, find the lowest entry greater than val
+// if abs < 0, find the highest entry less than val
+// if abs == 0, find the entry that equals val.
+// Currently does not work when val is outside the range of arry's values.
+Dygraph.binarySearch = function(val, arry, abs, low, high) {
+  if (low == null || high == null) {
+    low = 0;
+    high = arry.length - 1;
+  }
+  if (low > high) {
+    return -1;
+  }
+  if (abs == null) {
+    abs = 0;
+  }
+  var validIndex = function(idx) {
+    return idx >= 0 && idx < arry.length;
+  }
+  var mid = parseInt((low + high) / 2);
+  var element = arry[mid];
+  if (element == val) {
+    return mid;
+  }
+  if (element > val) {
+    if (abs > 0) {
+      // Accept if element > val, but also if prior element < val.
+      var idx = mid - 1;
+      if (validIndex(idx) && arry[idx] < val) {
+        return mid;
+      }
+    }
+    return Dygraph.binarySearch(val, arry, abs, low, mid - 1);    
+  }
+  if (element < val) {
+    if (abs < 0) {
+      // Accept if element < val, but also if prior element > val.
+      var idx = mid + 1;
+      if (validIndex(idx) && arry[idx] > val) {
+        return mid;
+      }
+    }
+    return Dygraph.binarySearch(val, arry, abs, mid + 1, high);
+  }
+}
+

 /**
  * Add ticks when the x axis has numbers on it (instead of dates)
  * TODO(konigsberg): Update comment.
  *
 /**
  * Add ticks when the x axis has numbers on it (instead of dates)
  * TODO(konigsberg): Update comment.
  *

- * @param {Number} startDate Start of the date window (millis since epoch)
- * @param {Number} endDate End of the date window (millis since epoch)
+ * @param {Number} minV minimum value
+ * @param {Number} maxV maximum value

  * @param self
  * @param {function} attribute accessor function.
  * @return {Array.<Object>} Array of {label, value} tuples.
  * @param self
  * @param {function} attribute accessor function.
  * @return {Array.<Object>} Array of {label, value} tuples.


@@ -1937,23 +2003,50 @@ Dygraph.numericTicks = function(minV, maxV, self, axis_props, vals) {
       ticks.push({v: vals[i]});
     }
   } else {
       ticks.push({v: vals[i]});
     }
   } else {

-    if (self.attr_("logscale")) {
-      // As opposed to the other ways for computing ticks, we're just going
-      // for nearby values. There's no reasonable way to scale the values
-      // (unless we want to show strings like "log(" + x + ")") in which case
-      // x can be integer values.
-
-      // so compute height / pixelsPerTick and move on.
+    if (axis_props && attr("logscale")) {

       var pixelsPerTick = attr('pixelsPerYLabel');
       var pixelsPerTick = attr('pixelsPerYLabel');

+      // NOTE(konigsberg): Dan, should self.height_ be self.plotter_.area.h?

       var nTicks  = Math.floor(self.height_ / pixelsPerTick);
       var nTicks  = Math.floor(self.height_ / pixelsPerTick);

-      var vv = minV;
-
-      // Construct the set of ticks.
-      for (var i = 0; i < nTicks; i++) {
-        ticks.push( {v: vv} );
-        vv = vv * Dygraph.LOG_SCALE;
+      var minIdx = Dygraph.binarySearch(minV, Dygraph.PREFERRED_LOG_TICK_VALUES, 1);
+      var maxIdx = Dygraph.binarySearch(maxV, Dygraph.PREFERRED_LOG_TICK_VALUES, -1);
+      if (minIdx == -1) {
+        minIdx = 0;

       }
       }

-    } else {
+      if (maxIdx == -1) {
+        maxIdx = Dygraph.PREFERRED_LOG_TICK_VALUES.length - 1;
+      }
+      // Count the number of tick values would appear, if we can get at least
+      // nTicks / 4 accept them.
+      var lastDisplayed = null;
+      if (maxIdx - minIdx >= nTicks / 4) {
+        var axisId = axis_props.yAxisId;
+        for (var idx = maxIdx; idx >= minIdx; idx--) {
+          var tickValue = Dygraph.PREFERRED_LOG_TICK_VALUES[idx];
+          var domCoord = axis_props.g.toDomYCoord(tickValue, axisId);
+          var tick = { v: tickValue };
+          if (lastDisplayed == null) {
+            lastDisplayed = {
+              tickValue : tickValue,
+              domCoord : domCoord
+            };
+          } else {
+            if (domCoord - lastDisplayed.domCoord >= pixelsPerTick) {
+              lastDisplayed = {
+                tickValue : tickValue,
+                domCoord : domCoord
+              };
+            } else {
+              tick.label = "";              
+            }
+          }
+          ticks.push(tick);
+        }
+        // Since we went in backwards order.
+        ticks.reverse();
+      }
+    }
+    // ticks.length won't be 0 if the log scale function finds values to insert.
+    if (ticks.length == 0) {

       // Basic idea:
       // Try labels every 1, 2, 5, 10, 20, 50, 100, etc.
       // Calculate the resulting tick spacing (i.e. this.height_ / nTicks).
       // Basic idea:
       // Try labels every 1, 2, 5, 10, 20, 50, 100, etc.
       // Calculate the resulting tick spacing (i.e. this.height_ / nTicks).


@@ -2009,26 +2102,29 @@ Dygraph.numericTicks = function(minV, maxV, self, axis_props, vals) {
   }
   var formatter = attr('yAxisLabelFormatter') ? attr('yAxisLabelFormatter') : attr('yValueFormatter'); 
 
   }
   var formatter = attr('yAxisLabelFormatter') ? attr('yAxisLabelFormatter') : attr('yValueFormatter'); 
 

+  // Add labels to the ticks.

   for (var i = 0; i < ticks.length; i++) {
   for (var i = 0; i < ticks.length; i++) {

-    var tickV = ticks[i].v;
-    var absTickV = Math.abs(tickV);
-    var label;
-    if (formatter != undefined) {
-      label = formatter(tickV);
-    } else {
-      label = Dygraph.round_(tickV, 2);
-    }
-    if (k_labels.length) {
-      // Round up to an appropriate unit.
-      var n = k*k*k*k;
-      for (var j = 3; j >= 0; j--, n /= k) {
-        if (absTickV >= n) {
-          label = Dygraph.round_(tickV / n, 1) + k_labels[j];
-          break;
+    if (ticks[i].label == null) {
+      var tickV = ticks[i].v;
+      var absTickV = Math.abs(tickV);
+      var label;
+      if (formatter != undefined) {
+        label = formatter(tickV);
+      } else {
+        label = Dygraph.round_(tickV, 2);
+      }
+      if (k_labels.length) {
+        // Round up to an appropriate unit.
+        var n = k*k*k*k;
+        for (var j = 3; j >= 0; j--, n /= k) {
+          if (absTickV >= n) {
+            label = Dygraph.round_(tickV / n, 1) + k_labels[j];
+            break;
+          }

         }
       }
         }
       }

+      ticks[i].label = label;

     }
     }

-    ticks[i].label = label;

   }
   return ticks;
 };
   }
   return ticks;
 };


@@ -2081,7 +2177,7 @@ Dygraph.prototype.extremeValues_ = function(series) {
  * number of axes, rolling averages, etc.
  */
 Dygraph.prototype.predraw_ = function() {
  * number of axes, rolling averages, etc.
  */
 Dygraph.prototype.predraw_ = function() {

-  // TODO(danvk): move more computations out of drawGraph_ and into here.
+  // TODO(danvk): movabilitye more computations out of drawGraph_ and into here.

   this.computeYAxes_();
 
   // Create a new plotter.
   this.computeYAxes_();
 
   // Create a new plotter.


@@ -2135,12 +2231,24 @@ Dygraph.prototype.drawGraph_ = function() {
 
     var seriesName = this.attr_("labels")[i];
     var connectSeparatedPoints = this.attr_('connectSeparatedPoints', i);
 
     var seriesName = this.attr_("labels")[i];
     var connectSeparatedPoints = this.attr_('connectSeparatedPoints', i);

+    var logScale = this.attr_('logscale', i);

 
     var series = [];
     for (var j = 0; j < data.length; j++) {
 
     var series = [];
     for (var j = 0; j < data.length; j++) {

-      if (data[j][i] != null || !connectSeparatedPoints) {
-        var date = data[j][0];
-        series.push([date, data[j][i]]);
+      var date = data[j][0];
+      var point = data[j][i];
+      if (logScale) {
+        // On the log scale, points less than zero do not exist.
+        // This will create a gap in the chart. Note that this ignores
+        // connectSeparatedPoints.
+        if (point < 0) {
+          point = null;
+        }
+        series.push([date, point]);
+      } else {
+        if (point != null || !connectSeparatedPoints) {
+          series.push([date, point]);
+        }

       }
     }
 
       }
     }
 


@@ -2254,7 +2362,7 @@ Dygraph.prototype.drawGraph_ = function() {
  *   indices are into the axes_ array.
  */
 Dygraph.prototype.computeYAxes_ = function() {
  *   indices are into the axes_ array.
  */
 Dygraph.prototype.computeYAxes_ = function() {

-  this.axes_ = [{}];  // always have at least one y-axis.
+  this.axes_ = [{ yAxisId : 0, g : this }];  // always have at least one y-axis.

   this.seriesToAxisMap_ = {};
 
   // Get a list of series names.
   this.seriesToAxisMap_ = {};
 
   // Get a list of series names.


@@ -2271,7 +2379,8 @@ Dygraph.prototype.computeYAxes_ = function() {
     'pixelsPerYLabel',
     'yAxisLabelWidth',
     'axisLabelFontSize',
     'pixelsPerYLabel',
     'yAxisLabelWidth',
     'axisLabelFontSize',

-    'axisTickSize'
+    'axisTickSize',
+    'logscale'

   ];
 
   // Copy global axis options over to the first axis.
   ];
 
   // Copy global axis options over to the first axis.


@@ -2294,9 +2403,12 @@ Dygraph.prototype.computeYAxes_ = function() {
       var opts = {};
       Dygraph.update(opts, this.axes_[0]);
       Dygraph.update(opts, { valueRange: null });  // shouldn't inherit this.
       var opts = {};
       Dygraph.update(opts, this.axes_[0]);
       Dygraph.update(opts, { valueRange: null });  // shouldn't inherit this.

+      var yAxisId = this.axes_.length;
+      opts.yAxisId = yAxisId;
+      opts.g = this;

       Dygraph.update(opts, axis);
       this.axes_.push(opts);
       Dygraph.update(opts, axis);
       this.axes_.push(opts);

-      this.seriesToAxisMap_[seriesName] = this.axes_.length - 1;
+      this.seriesToAxisMap_[seriesName] = yAxisId;

     }
   }
 
     }
   }
 


@@ -2359,7 +2471,6 @@ Dygraph.prototype.computeYAxisRanges_ = function(extremes) {
 
   // Compute extreme values, a span and tick marks for each axis.
   for (var i = 0; i < this.axes_.length; i++) {
 
   // Compute extreme values, a span and tick marks for each axis.
   for (var i = 0; i < this.axes_.length; i++) {

-    var isLogScale = this.attr_("logscale");

     var axis = this.axes_[i];
     if (axis.valueWindow) {
       // This is only set if the user has zoomed on the y-axis. It is never set
     var axis = this.axes_[i];
     if (axis.valueWindow) {
       // This is only set if the user has zoomed on the y-axis. It is never set


@@ -2387,7 +2498,7 @@ Dygraph.prototype.computeYAxisRanges_ = function(extremes) {
 
       var maxAxisY;
       var minAxisY;
 
       var maxAxisY;
       var minAxisY;

-      if (isLogScale) {
+      if (axis.logscale) {

         var maxAxisY = maxY + 0.1 * span;
         var minAxisY = minY;
       } else {
         var maxAxisY = maxY + 0.1 * span;
         var minAxisY = minY;
       } else {