From 6d0aaa096fa90889f5370cc02933cf3cfc1a5777 Mon Sep 17 00:00:00 2001
From: Dan Vanderkam <dan@dygraphs.com>
Date: Wed, 2 Mar 2011 19:37:35 -0500
Subject: [PATCH] A warning and better default behavior when labels option and
 CSV labels are both present

---
 dygraph.js | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/dygraph.js b/dygraph.js
index 7f312b6..529552d 100644
--- a/dygraph.js
+++ b/dygraph.js
@@ -2965,13 +2965,30 @@ Dygraph.prototype.parseCSV_ = function(data) {
     if (ret.length > 0 && fields[0] < ret[ret.length - 1][0]) {
       outOfOrder = true;
     }
-    ret.push(fields);
 
     if (fields.length != expectedCols) {
       this.error("Number of columns in line " + i + " (" + fields.length +
                  ") does not agree with number of labels (" + expectedCols +
                  ") " + line);
     }
+
+    // If the user specified the 'labels' option and none of the cells of the
+    // first row parsed correctly, then they probably double-specified the
+    // labels. We go with the values set in the option, discard this row and
+    // log a warning to the JS console.
+    if (i == 0 && this.attr_('labels')) {
+      var all_null = true;
+      for (var j = 0; all_null && j < fields.length; j++) {
+        if (fields[j]) all_null = false;
+      }
+      if (all_null) {
+        this.warn("The dygraphs 'labels' option is set, but the first row of " +
+                  "CSV data ('" + line + "') appears to also contain labels. " +
+                  "Will drop the CSV labels and use the option labels.");
+        continue;
+      }
+    }
+    ret.push(fields);
   }
 
   if (outOfOrder) {
-- 
2.7.4