From 4ecb55b5c66f7723d1f5c588af62855bd4c06faa Mon Sep 17 00:00:00 2001
From: Robert Konigsberg <konigsberg@google.com>
Date: Thu, 21 Feb 2013 15:46:01 -0500
Subject: [PATCH] Fix bug 436. Only restore axes that remain after an option
 update.

---
 auto_tests/tests/multiple_axes.js | 24 ++++++++++++++++++++++++
 dygraph.js                        |  7 ++++++-
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/auto_tests/tests/multiple_axes.js b/auto_tests/tests/multiple_axes.js
index 3033190..8d94803 100644
--- a/auto_tests/tests/multiple_axes.js
+++ b/auto_tests/tests/multiple_axes.js
@@ -257,3 +257,27 @@ MultipleAxesTestCase.prototype.testDrawPointCallback = function() {
   assertEquals(1, results.y2["Y3"]);
   assertEquals(1, results.y2["Y4"]);
 };
+
+// Test for http://code.google.com/p/dygraphs/issues/detail?id=436
+MultipleAxesTestCase.prototype.testRemovingSecondAxis = function() {
+  var data = MultipleAxesTestCase.getData();
+
+  var results = { y : {}, y2 : {}};
+
+  g = new Dygraph(
+    document.getElementById("graph"),
+    data,
+    {
+      labels: [ 'Date', 'Y1', 'Y2', 'Y3', 'Y4' ],
+      drawPoints : true,
+      pointSize : 3,
+      series : {
+        'Y4': {
+          axis: 'y2'
+        }
+      },
+    }
+  );
+
+ g.updateOptions({ series : { Y4 : { axis : 'y' } } });
+};
diff --git a/dygraph.js b/dygraph.js
index f198cff..9a5be72 100644
--- a/dygraph.js
+++ b/dygraph.js
@@ -2472,7 +2472,12 @@ Dygraph.prototype.computeYAxes_ = function() {
 
   if (valueWindows !== undefined) {
     // Restore valueWindow settings.
-    for (index = 0; index < valueWindows.length; index++) {
+
+    // When going from two axes back to one, we only restore
+    // one axis.
+    var idxCount = Math.min(valueWindows.length, this.axes_.length);
+
+    for (index = 0; index < idxCount; index++) {
       this.axes_[index].valueWindow = valueWindows[index];
     }
   }
-- 
2.7.4