Repository: vega/altair

Issue:
Candlestick gallery example has no data visible
The example on the website https://altair-viz.github.io/gallery/candlestick_chart.html#gallery-candlestick-chart shows axis and vertical rules, but no bars of data.  

I have copied the code locally and run it and get the same result.


Discussion:
I just checked on my laptop and on my mobile phone, perhaps try again or refresh?  It might have been a momentary issue.
Do you have adblock? Sometimes adblock overzealously blocks Vega-Lite from accessing URL data sources.
Thanks for the comments.

I have checked this on Windows, OSX, and iOS and see the following:

- iOS the gallery website version works
- mac OSX on Safari the website and local host jupyter notebook both work
- mac OSX on Firefox 60.0.1 (64-bit) both the website and the localhost jupiter notebook have the issue (Ad blocking is turned off)
- Windows 10 Firefox 59.0.3 (64-bit) both the website and the localhost jupiter notebook have the issue (Ad blocking is turned off) 
- Windows 10 Edge browser the website has the issue

**Note** All the other examples in the gallery that I looked at worked and when I have made visualizations in a jupyter notebook I have gotten them to work as expected on Firefox on both the Mac and Windows 10.  The only time I have seen this issue is with the Candlestick example in the combinations of browser/OS described above.

Let me know what else I can do the help diagnose/fix this issue.
Is there any error in the javascript console when the chart fails to show?
Also, if you click "Open in Vega Editor", does the chart fail to show there as well?
When loading the page from the docs I get the following errors in the console:
```
Blocked loading mixed active content “http://localhost:8888/static/components/font-awesome/fonts/fontawesome-webfont.woff2?v=4.7.0”[Learn More]
modernizr.min.js:4:3946

WARN A scale with zero=false is used with bar mark. This can be misleading as the height of the bar can be arbitrary based on the scale domain. You may want to use point mark instead.
vega-lite@2.4:1:1350

Source map error: TypeError: NetworkError when attempting to fetch resource.
Resource URL: moz-extension://2fa4c84f-4d79-7042-a05f-a17181857d8b/browser-polyfill.js
Source Map URL: browser-polyfill.js.map[Learn More]
```

When I open in the Vega Editor the chart looks the same with no bars and the warning `[Warning] A scale with zero=false is used with bar mark. This can be misleading as the height of the bar can be arbitrary based on the scale domain. You may want to use point mark instead.` is repeated twice.

This was done on mac osx Firefox 60.0.1 (64-bit).
The warning is not a problem, but the "Source map error" indicates something is wrong. I'd raise the issue on the Vega-Lite repo: we can't do anything in this repository to address this kind of error.
@jakevdp Thanks for the help.  I am getting started with altair and I am not sure how to make a minimal example in vega-lite to test/show the issue.  Can I just use the altair docs example?  If not, how is the best way to get the generated vega-lite code out of the python/html to add to the issue?



I see the "view source" link now.  Working on the issue now.

Resolving patch:
diff --git a/altair/vegalite/v2/examples/candlestick_chart.py b/altair/vegalite/v2/examples/candlestick_chart.py
--- a/altair/vegalite/v2/examples/candlestick_chart.py
+++ b/altair/vegalite/v2/examples/candlestick_chart.py
@@ -10,7 +10,7 @@
 df = pd.DataFrame(
 [
       {
-        "date": "01-Jun-2009",
+        "date": "2009-06-01",
         "open": 28.7,
         "high": 30.05,
         "low": 28.45,
@@ -19,7 +19,7 @@
         "ret": -4.89396411092985
       },
       {
-        "date": "02-Jun-2009",
+        "date": "2009-06-02",
         "open": 30.04,
         "high": 30.13,
         "low": 28.3,
@@ -28,7 +28,7 @@
         "ret": -0.322580645161295
       },
       {
-        "date": "03-Jun-2009",
+        "date": "2009-06-03",
         "open": 29.62,
         "high": 31.79,
         "low": 29.62,
@@ -37,7 +37,7 @@
         "ret": 3.68663594470045
       },
       {
-        "date": "04-Jun-2009",
+        "date": "2009-06-04",
         "open": 31.02,
         "high": 31.02,
         "low": 29.92,
@@ -46,7 +46,7 @@
         "ret": 4.51010886469673
       },
       {
-        "date": "05-Jun-2009",
+        "date": "2009-06-05",
         "open": 29.39,
         "high": 30.81,
         "low": 28.85,
@@ -55,7 +55,7 @@
         "ret": 6.08424336973478
       },
       {
-        "date": "08-Jun-2009",
+        "date": "2009-06-08",
         "open": 30.84,
         "high": 31.82,
         "low": 26.41,
@@ -64,7 +64,7 @@
         "ret": 1.2539184952978
       },
       {
-        "date": "09-Jun-2009",
+        "date": "2009-06-09",
         "open": 29.77,
         "high": 29.77,
         "low": 27.79,
@@ -73,7 +73,7 @@
         "ret": -5.02431118314424
       },
       {
-        "date": "10-Jun-2009",
+        "date": "2009-06-10",
         "open": 26.9,
         "high": 29.74,
         "low": 26.9,
@@ -82,7 +82,7 @@
         "ret": -5.46623794212217
       },
       {
-        "date": "11-Jun-2009",
+        "date": "2009-06-11",
         "open": 27.36,
         "high": 28.11,
         "low": 26.81,
@@ -91,7 +91,7 @@
         "ret": -8.3743842364532
       },
       {
-        "date": "12-Jun-2009",
+        "date": "2009-06-12",
         "open": 28.08,
         "high": 28.5,
         "low": 27.73,
@@ -100,7 +100,7 @@
         "ret": -5.52763819095477
       },
       {
-        "date": "15-Jun-2009",
+        "date": "2009-06-15",
         "open": 29.7,
         "high": 31.09,
         "low": 29.64,
@@ -109,7 +109,7 @@
         "ret": 3.4920634920635
       },
       {
-        "date": "16-Jun-2009",
+        "date": "2009-06-16",
         "open": 30.81,
         "high": 32.75,
         "low": 30.07,
@@ -118,7 +118,7 @@
         "ret": 0.155038759689914
       },
       {
-        "date": "17-Jun-2009",
+        "date": "2009-06-17",
         "open": 31.19,
         "high": 32.77,
         "low": 30.64,
@@ -127,7 +127,7 @@
         "ret": 5.82822085889571
       },
       {
-        "date": "18-Jun-2009",
+        "date": "2009-06-18",
         "open": 31.54,
         "high": 31.54,
         "low": 29.6,
@@ -136,7 +136,7 @@
         "ret": 8.17610062893082
       },
       {
-        "date": "19-Jun-2009",
+        "date": "2009-06-19",
         "open": 29.16,
         "high": 29.32,
         "low": 27.56,
@@ -145,7 +145,7 @@
         "ret": 8.59872611464968
       },
       {
-        "date": "22-Jun-2009",
+        "date": "2009-06-22",
         "open": 30.4,
         "high": 32.05,
         "low": 30.3,
@@ -154,7 +154,7 @@
         "ret": 15.4907975460123
       },
       {
-        "date": "23-Jun-2009",
+        "date": "2009-06-23",
         "open": 31.3,
         "high": 31.54,
         "low": 27.83,
@@ -163,7 +163,7 @@
         "ret": 11.7370892018779
       },
       {
-        "date": "24-Jun-2009",
+        "date": "2009-06-24",
         "open": 30.58,
         "high": 30.58,
         "low": 28.79,
@@ -172,7 +172,7 @@
         "ret": -10.4234527687296
       },
       {
-        "date": "25-Jun-2009",
+        "date": "2009-06-25",
         "open": 29.45,
         "high": 29.56,
         "low": 26.3,
@@ -181,7 +181,7 @@
         "ret": 0
       },
       {
-        "date": "26-Jun-2009",
+        "date": "2009-06-26",
         "open": 27.09,
         "high": 27.22,
         "low": 25.76,
@@ -190,7 +190,7 @@
         "ret": 0
       },
       {
-        "date": "29-Jun-2009",
+        "date": "2009-06-29",
         "open": 25.93,
         "high": 27.18,
         "low": 25.29,
@@ -199,7 +199,7 @@
         "ret": 5.26315789473684
       },
       {
-        "date": "30-Jun-2009",
+        "date": "2009-06-30",
         "open": 25.36,
         "high": 27.38,
         "low": 25.02,


Test patch: