#2072 polar mode - section of the circle
Hello!
In the polar mode it is sometimes good to plot some data only in a section of the whole circle (ie. of the polar grid). In the previous versions (5.0) this could be done by setting the lower range of the x and/or y axis to 0. However, this doesn't work in the current version (5.2.4) - the whole circle of the polar grid is always drawn.
Another thing is that if I plot the data with errorbars, the dashes at the ends of the errorbars are clipped to the edges defined by xmin and ymin, which doesn't look good. The latter behaviour has not changed since version 5.0.
Please see the attached pictures and the script to generate them in both versions.
Is there a way to make a nice plot in a section of the polar grid? It would be perfect to make it possible also in any fraction of the circle, not only clipping at 90° or 180°.
Anyway, thank you for gnuplot, it is a magnificent tool.
Here are the other two attachments.
In gnuplot 5 page layout in polar mode is largely distinct from the normal x/y cartesian mode. You can still use limits on x and y to draw to only a portion of the plane if necessary, but it sounds like that is exactly what you do not want to do. If I understand correctly, you should let x and y autoscale so that the plot fits on the page but limit the polar coordinates theta and R directly:
set xrange [:]
set yrange [:]
set rrange [0 : 1.5]
set trange [0: pi/2]
If I have misunderstood what you want, please clarify.
Note that there is currently a bug in the interpretation of "set trange" - it always expects angles in radians rather than degrees. I just learned this yesterday (does nobody use angles in degrees?). The fix is probably trivial but until the next bugfix release of gnuplot you will have to work around this by specifying the theta range in radians as shown above.
The documentation may not be clear, in which case any suggestions for improving it are welcome. Was there a particular section that caused confusion?
Last edit: Ethan Merritt 2018-09-12
I think I misunderstood. It's not the data you want to limit but the polar grid marks? Yeah, that was an unintended change between 5.0 and 5.2 I will look into repairing that.
Fix will be in 5.2.5
Thank you.
That is exactly what I need - to limit the polar grid marks, not the data itself.
But there is also the other thing I mentioned, ie. the tics at the ends of the errorbars. Currently they are clipped to xmin and ymin, what I marked with small circles on my pictures.
Anyway, setting trange in degrees works for me (for plotting functions, not data) provided that I write "set angles degrees".
I changed the error bar clipping also. The cross at the end is now either drawn or not drawn in its entirety based on whether the endpoint of the bar is clipped. Thanks for pointing out these problems. Bugs only get fixed if someone notices and reports them. I added a new unit test to the demo collection that exercises the affected code.