Null values in Annotated Timeline about google-visualization-issues HOT 44 CLOSED

This should be an option (if at all), as the default behavior should remain as it is
today - to draw the line 
between the existing data points.

Agreed, an option would be good. 
I do feel though that a straight line between data points either side of a null or
nulls 
suggests there is data for that period (at least visually) rather than a genuine break
in the 
data. 
Interestingly the Image Line Chart and Sparkline graphs do handle nulls in this way.

Agree that this would be nice, but it should be an option.  Not high priority in my
book though.

Agreed! It would be nice for motion charts as well.

Lisa, 
Thanks for your response. I do feel that this is an issue which is fundamental to the

way in which data is handled and viewed on this graph. 
I work for King's College London running the London Air Quality monitoring network

(www.londonair.org.uk)
The annotated timeline would be perfect for displaying pollution levels measured at

sites around the city but the analysers often break and so there are often breaks in

the data with nulls in the dataset.
If the graph draws a line between two points (say midnight one day to midnight the

next) over a period of nulls then to the public it will look like the pollution level

was flat or rising over that day rather than the reality which is that there was no

data recorded that day.
We would absolutely love to use the annotated timeline on our site, but we can't until

this issue is solved.
Andrew Grieve
[email protected]

Comment to AndyJessCalendar:
I do not work for/at Google.  I was agreeing with you.  I would also like for this
item to be fixed -- with an option of whether to show a break in the line or to
"connect the dots".

Ah, Sorry Lisa, my mistake. 
Well, let's hope they see the conversation thread and the other folks who would also

like to see this fixed and escalate it's priority.
Andrew

Hello Razbarvaz,
I know this issue has been accepted and is low priority but do you have an estimate
of 
when a fix will be released? 
Very keen to use annotated timeline on our site.

Thanks,
Andrew

I also agree that this feature would be highly beneficial. I am using the annotated
time line to show nutrient concentration levels in stream water alongside discharge
levels and the connecting line is very misleading!

AnnotatedTimeLine should definitely not display a connecting line between 2 points if
there are null values inside the 2 points interval. At least for the use cases I have.

Regards,

Dan

I'm a statistician guy, and I've dealt with data visualization packages such as R, SPSS,
etc. in the past. I feel this behavior in gviz is definitely wrong.

I'm currently developing a webapp for real-time monitoring of a wide area wireless
network. I do use the annotated time line, but my audience is mislead when lines are
drawn for null values (e.g. when a network site goes down then goes up, one can't notice
a problem occurred. My current fix is to replace null values with zeros).

This is a high priority issue, in my opinion.

Regards.
Theo

I believe the method in which null values are handled should be optional.  I personally
would not want to see a gap in the line when null values are present.  Instead, I'd
prefer to continue graphing with the previous non-null value in the timeline.  

I'm trying to visualize changes to an inventory stock level over time based on key
business events.  If I have an event that removes ten widgets from inventory, I want
the inventory value to go down by 10 units, but the new inventory level should remain
the same for the rest of the timeline until the next event occurs that impact inventory
levels.  Just because we had no orders doesn't mean our inventory disappeared.

The only work around I have currently is to generate data sets for days in which no
activity occurs.  This is a lot of data to pass unnecessarily. 

It seems to me that whenever the Annotated Timeline is used to displayed sensor-collected
data - gaps should be displayed. (Hardware) sensors are simply unreliable that way.

Agreed;

1. This should not happen by default (hence an option of sorts)
2. Also if data is passed as {mon,teu,wed,thu,fri,mon} then Gviz should not add sat+sun
between fri and mon. 
3. The priority level should go up. 
4. How come Google Finance  does this ? eg.

http://www.google.com/finance?chdnp=1&chdd=1&chds=1&chdv=1&chvs=maximized&chdeh=0&chfdeh=0&chdet=1285272000000&chddm=1955&chls=IntervalBasedLine&q=NASDAQ:SCHL&ntsp=0

Let us know and thank you in advance

Regards, 
Ash

+1
I also don't understand why this issue has a low priority. I also require the described
behavior of the Annotated Timeline. Of course it shouldn't be done by default, but
it should be available via options.

Hm, by the way, to make it clear. There only should not be a line between existing data
points. On Google finance, as ashaar.shaikh has shown, they remove time. These are
two different things. However, it could be another option as well.

Absolutely this feature should be added. If no data exists right now, a line is drawn
and can easily be misinterpreted. Please up the priority on this!

It's great to see so many people agreeing with my original feature request. 
As you can see though i raised this over a year ago and nothing has happened, nada,
not a squeak. 
I gave up and used dygraphs instead, much better for use with scientific datasets and
because they're done in javascript - no need for flash plugin.
danvk.org/dygraphs/

Andy

I agree. Data shouldn't be interpolated in some cases and in my humble opinion this
option is a must and no low priority enhancement.

I am using dygraph because of this issue. There are some subtleties that ought to be
implemented in Annotated timeline:

* Null is sometimes a break in data values and sometimes not. The line drawing needs
an option (by column) to decide whether to draw a line 'over nulls' or break it.
* NaN is always a break.

My data consists of weather readings. If the temperature readings from two stations
are plotted on the same chart then (typically) the readings are not taken at exactly
the same time. This means that (typically) each row in the DataTable only has a reading
from one station and the other is null. This is the case to draw lines over nulls.
However, one station can go offline, and then you want a way to signal that line break.
Hence the use of NaN.

Philip

Absolutely hope this gets sorted out. Would love to have the option.

Agreed, this issue needs to be sorted out.

Very important feature for our team too. Google already does this in its Google Finance
charts:
http://www.google.com//finance?chdnp=1&chdd=1&chds=1&chdv=1&chvs=maximized&chdeh=0&chfdeh=0&chdet=1310745480000&chddm=825&chls=IntervalBasedLine&q=NASDAQ:GOOG&ntsp=0

The date range feature would also be nice,

Agreed, this issue should be sorted out.

I need this! I can't use the timeline without it unfortunately.

Guys, you should try Flot instead.

In a time series (for example a daily event count) the days with no event appears as
missing, but it would be better treat them as zero values (i.e. “0” events). This would
be another useful option. 

Giovanni

Unfortunately when the represented series can contain zero value normally (for e.g.
temperatures is °C), filling data gaps with zero values could be misleading. 

BTW it is one of the oldest issues, it has an accepted status, it has one of the most
stars and still nothing has been done.

it's true, nevertheless there are time-series without zero values. in these cases why
not? 

Could you tell if there’s any hope to get this issue solved?

This is a major issue for me too, any chance of a fix?

It's the only thing holding us back from integrating Google Visualizations into our
suite of Habitat monitoring and environmental/conservation efforts.

This is a major issue, which seems trivial to solve. I can't believe that nothing has
happened since this was reported over three years ago now.

I think that Annotated Timeline is now deprecated. The existing line charts do support
having breaks in the data. Although, if you are plotting multiple lines on the same
axes and sometimes want the line to extend across missing values and sometimes not,
then it is more complicated to do (but doable)

I was hoping Google implemented this feature request as much as all of you, but suddenly
I realized why they don't do it, and here's the reason as I understand it:

Annotated Timeline takes as input Date objects and your graphed value.
Date objects specify time with up to a millisecond precision.

It does NOT require that your Dates are spaced-out regularly (every hour), it just
requires you provide WHEN an event occurred with up to millisecond precision and the
scalar data to show for that event.

IF they had to put zeroes everywhere there's no data, it would become useless, since
everywhere would be zeroes but only in the milliseconds where there are events would
you see a "Dirac's delta" showing the data, but inmediately the millisecond after they
would need to put a Zero.

So if you dont want all the milliseconds to be Zero, you have to say for how long you
want to show data everythime there's an event (say 1 hour).

I'm not sure I made myself clear :)

Elias Baixas

SO The solution is:
chose a time interval, say 1 hour, translate your graphed events to be "magnitude in
one hour",

then after each event, if there's no "real data", put a zero, and pass it along to
google Timeline.

This is not a solution. There are many cases where zero values cannot represent "NoData".
For e.g. in a temperature graph zero values can occur (just like now during the winter
time), representing missing data with zero values is misleading.

Your first post is not correct either. The behaviour we want is to stop plotting the
line at the last value before the "NoData" point and start plotting where there is
an actual data after a "NoData" point. You don't have to assign anything to the milliseconds
between the actual data points. It's only a matter of representation of the data series.


Forget the zero. This case is about 'Nodata'. 

Understood,

it's just that my issue was different, I didn't get that your problem was with representing
NoData.

Anyway, my solution can be useful for some.

Thanks !

Now it's implemented!, i'm using google charts+grails plugin, if you pass null value
in the array of data then line breaks and continues the next value, great!

That is a Line Chart, not Annotated Timeline. Line Charts already had this feature.

Hi! It's corrected with the new API! :-D

https://developers.google.com/chart/interactive/docs/gallery/annotationchart

As noted by iforci, the new AnnotationChart supports null values in the data to leave
a gap in the line.

This is great, but where is the option to revert to the old behavior?

Ryan,

Though it is not documented yet, you can turn on the 'interpolateNulls' option under
the 'chart' option, like so:

var options = {
  chart: {
    interpolateNulls: true
  }
};