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Line Chart Bug?

zax

Hi,<br />
<br />
I have a line graph with a lot of points, and when there is a gap in the data I (and more importantly my boss) would like there to be no line drawn. So I unchecked "Connect Missing Values" and nothing happened. Arrgh. <br />
<br />

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zax

Only me? OK well I am guessing that there is something in my reports preventing this function from working properly. My plan is to rebuild the report in small steps and try and find what is causing this...

zax

In case anyone else might be want to help me, I have attached a CSV file (as a data source) and a copy of the graph. In the data file you will see there are no rows between:

2012-07-13 11:16:30 and 2012-07-13 13:13:53

But a line is still drawn. I am guessing a chart engine bug, but I don't know what is causing it. If someone can confirm it is a bug I could report it.

Thanks,
Stephen

BRM

I don't have a ready solution for you but are you sure the series you are trying to modify is the one you have provided the dialog box for? The dialog suggests the series line color should be black and in your screen shot it is blue. You may not be modifying the properties of the correct series.

zax

Yes. What you can't see in that first screenshot is that I am using the series palette which is why the line is blue. In my example there is only one series in the chart.

I really cannot understand why the chart engine is doing this. With a graph with say, 6 points, it works fine. But with a graph with hundreds or thousands of points, the "(Don't) Connect Missing Values" functionality seems to stop working.

I have tried to make the example attached to my previous post as simple as possible, to exclude other weirdness (scripting etc). I have also tried this in Eclipse Juno 4.2, with the same result. So if it is a bug it is in the latest version too.

My options are running out I guess.. if the XML contains the correct value (i.e. "false") and the line is still being drawn... I have to break the news to the customer. If anyone has a magic bullet, please let me know.

Thanks,
Stephen

zax

Nobody likes admitting publicly they are an idiot. But this time I have to say I am an idiot. The missing points require there to be null or empty values passed in with a time. I was assuming that the charting engine knew to expect a data point every second. Of course it does not know this, so when there is a gap in the data.. it will connect the two data points spanning the absent data.

SO THIS IS DEFINITELY NOT A BUG.

So now I need to find a clever way to manufacture the missing time data points and set them to null, so the charting engine will not draw a line.

My initial thoughts are:
1. A MySQL Procedure
2. Iterate over the result returned from the query in BIRT
3. Create a calendar table in the database and join to that.

Any thoughts?

BRM

If your data will always be displayed on some fixed interval like the 6 to 17 in your example then creating a calendar/time table in the db and left joining your data to it would strike me as easiest.