[reportlab-users] Bar/plot combo chart with labels for endpoint values?

Robin Becker robin at reportlab.com
Mon Feb 4 13:10:45 EST 2008

Stevens, Ian wrote:

> Can the open source version of Reportlab be used to create a combo bar

> and plot chart? Is it also possible to label the endpoint values of

> plots on a plot chart? If not, are these features available in the

> commercial version?


> Here's an example of what I'm talking about:


> https://hermes.manulife.com/Canada/wmCentralObjects.nsf/LookupFiles/Q420

> 05i-WatchChartIWM_Balanced_Q4_2005/$File/IWM_Balanced_Q4_2005.gif


> thanks,

> Ian.

we've certainly done bespoke charts that look similar, but there isn't anything
builtin that just does all of the features. To do this kind of chart I believe
the process is

1) derive from the barchart; set up grids etc etc etc.
2) ensure the scales are set up so everything on the y axis will work. That's
probably best done by overriding the draw method.
3) draw the bar chart.
4) add stuff like the lines and annotations explicitly using the scales set up
by the bar chart.

It's not exactly clear from the exemplar whether the cumulative line plots are
smooth or not? Clearly the barchart is quarterly ie regularly spaced on the
x-axis, but the lineplots could be on a daily/monthly support etc etc which
would complicate stuff.
Robin Becker

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