GNOME Bugzilla – Bug 698534
Support interpolation for line plots
Last modified: 2013-04-25 06:49:51 UTC
When opening the file attached to bug #698388 we get the warning: Unknown interpolation type encountered: 'b-spline', using Bezier cubic spline instead. But there does not seem to be _any_ interpolation type used in th eobjects of this file.
I guess that this is simply a case of us not supporting interpolation types for line plots. Why not?
line plots are discrete plots. I don't see what an interpolation means in this situation.
Jean, perhaps you could have a look at the file attached to bug #698388 and see whether we import it as the wrong plot style. LO uses interpolation, we import as lineplot and don't have interpolation there.
I suppose that closed splines don't apply to line plots. The issue is that there is no way to remove them from the list without breaking the API. Do we also need interpolation in area plots?
Andreas, one more question: for line plots, Bezier cubic splines and natural cubic splines should be just identical, may be we should only use natural cubic splines there?
Jean, I am somewhat worried about the import from ODF. In ODF the interpolation type is part of the style. We translate the ODF style information into the Gnumeric/Goffice info when we read the style. Later when the style is applied to a graph we just check that the property exists and then pass the property value to the graph. For this to work it would be nice if all plots would accept all interpolation types. Of course two interpolation types that yield the same result could then be mapped internally to one of them, it. with respect to line plots, Bezier cubic splines could be considered a synonym for natural cubic splines.
It is possible to replace the non supported interpolation types in gog_series_set_property().
This problem has been fixed in our software repository. The fix will go into the next software release. Thank you for your bug report.
Jean, thank you very much! It seems to me that the 'skip invalid data' checkbox has no effect. If the file is opened in LO, the missing data points seem cause a break in the curves. In Gnumeric we interpolate across those missing values it seems even if the skip invalid data is unchecked. (For xy-plots we also create breaks.)
Just forgot that, will fix.
Actually, I tried to have the same behavior than before: skip invalid for normal line plots and don't skip for all others. Just things don't work and I don't know why.
Fixed. The check box is now hidden for line and area plots (using a very bad hack), and there is a break for missing data in normal line plots (but not in stacked lines or in any area plot as before).