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Thu, 26 February 2015 08:53

Eclipse User

Hi, I'm new to BIRT but am getting on quite well even with my beginner level knowledge of code.

Can anyone help me implement a reversed running sum for a line chart? Essentially the same as a normal running sum but one that ends on zero rather than starting on zero.

The data I'd like to display has two series, both represent the first derivative of a variable. The first series is history data, the second is forecast data. I have a running sum on the forecast data and would like to display the history data inline with it. If the two series could meet at zero that would be perfect.

Any ideas welcome : )

Re: Deccumulation? [message #1638595 is a reply to message #1637023]

Fri, 27 February 2015 02:36

Eclipse User

Or, if no one can think of a way to script this I can perform a union in the SQL query. In which case I have new questions;

Is it possible to set some kind of reference point on the X-axis for where to start the accumulation (naively hoping that history data will just fall into line)
Or more realistically; Can I set markers on the Y-axis at all points where my series crosses the midnight values on the X-axis?

[Updated on: Fri, 27 February 2015 02:37] by Moderator

Re: Deccumulation? [message #1640017 is a reply to message #1638595]

Fri, 27 February 2015 18:15

Eclipse User

I've been trying a few things out and might be able to narrow down my questions. Combining the series in the SQL query helps with other things so I'm running with that atm.

Can I subtract the entire series by it's value at a specific row number on the chart? Row number 24 for example.

And is there a way to add markers on the x-axis (Datetime) at regular intervals? Such as 00:00 each day?
Under normal data flows this would also have a static row number so I can go with that. It feels like a bit of a workaround, but I've done everything I can to make the data flow into the SQL database as stable as possible so I can live with this much.

Any other ideas such as methods of preprocessing in BIRT welcome.

Re: Deccumulation? [message #1643817 is a reply to message #1640017]

Sun, 01 March 2015 14:42

Eclipse User

Could really do with some pointers.

If I put my data into a table, will I be able to access the value in a specific column and row number for use in a chart expression?

[Updated on: Sun, 01 March 2015 14:43] by Moderator

Re: Deccumulation? [message #1652481 is a reply to message #1643817]

Thu, 05 March 2015 17:28

Eclipse User

Sorry for the delay. So, you want to take say, a month's data and start at the full value of the month and have each bar step down til the last day of the month based on the sales or whatever for each given day? Am I understanding correctly?

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