CairoMakie - Controlling radial axes in polar plots

Specific Domains Visualization
1

I can’t quite fathom the logic CM uses for the radial axes interval for polar plots. The default seems to be 45 degrees, but if (say) the thetalimits = (-pi/6 to +pi/6), the axes are at 10 degree intervals. In the documentation, I see other intervals, e.g. 15 degrees but I don’t see where they are chosen. I want to plot a function over 0..2pi but I want to control the interval for the radial axes myself. I am sure this is a dumb question. I am using Julia 1-11-1 with CairoMakie v0.12.15

E.g. This bit of code produces a 15 degree interval

using CairoMakie
fig = Figure()
ax = PolarAxis(fig[1, 1], thetalimits = (0, pi))
lines!(ax, range(0, pi, length=100), 10 .+ sin.(0.3 .* (1:100)))
fig

whereas this bit of code produces a 10 degree interval:

using CairoMakie
f = Figure(size = (600, 600))
ax = PolarAxis(f[1, 2], title = "thetalimits", thetalimits = (-pi/6, pi/6))
lines!(ax, range(0, 8pi, length=300), range(0, 10, length=300))
f

Roger

2

The default for thetaticks is of type AngularTicks. That is basically a wrapper for the default tick finder just that it pretransforms radians to degrees and adds the degree symbol as a suffix. It tries to find “nice” ticks in the given limits, that’s why you get different intervals for different limits.

If you want to pass custom ticks the most basic thing that works is a tuple where the first argument is a vector of numbers (in radians) and the other is a vector of labels for those tick locations. That’s probably not documented more extensively because the mechanism is the same for Axis, Axis3 and Colorbar

3

@jules Many thanks for that. I did read the Axis and Axis3D sections before posting the question but didn’t find exactly what I wanted, probably it was there but my understanding is not great. But no worries, I re-read the documentation. Obviously, I could just create the data to produce the radial lines I wanted and hide everything else.

4

No worries, it takes time to get used to the way Makie does things :slight_smile:

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