How to plot polar contourplot in julia

usman0311 · December 16, 2021, 11:59am

In material science, we frequently have to plot pole figures to know the symmetry of the as-grown thin film.
The Pole figure is a polar contour plot. I struggle to plot it in Julia. It would be a great help if someone helped me out.
The pole figure should look like:

But what I am getting is like

I m using the following script:

using DataFrames, Plots, DelimitedFiles, Glob, LaTeXStrings

f=Glob.glob("*.txt")

df=readdlm(f[1],comment_char='#',comments=true)
df=DataFrame(df,:auto)

Chi,phi,I=df[:,1],df[:,2],df[:,3]

plotlyjs()

c=contour(Chi,phi,I,fill=true,c=:Spectral,frame=:box,axis=:polar,xlabel=L"$\chi$",ylabel=L"$\phi$", width=1000, height=1000)
savefig(c,"pole122.png")

juliohm · December 16, 2021, 12:06pm

Maybe you want the option proj = :polar.

usman0311 · December 16, 2021, 12:56pm

Its not working, I am getting following error:

MethodError: no method matching heatmap_edges(::Vector{Float64}, ::Symbol, ::Vector{Float64}, ::Symbol, ::Tuple{Int64})
Closest candidates are:
  heatmap_edges(::AbstractVector, ::Symbol, ::AbstractVector, ::Symbol, ::Tuple{Int64, Int64}) at C:\Users\usmaa\.julia\packages\Plots\FCM0H\src\utils.jl:304
  heatmap_edges(::AbstractVector, ::Symbol, ::AbstractVector, ::Symbol, ::Tuple{Int64, Int64}, ::Bool) at C:\Users\usmaa\.julia\packages\Plots\FCM0H\src\utils.jl:304
  heatmap_edges(::AbstractVector, ::Symbol) at C:\Users\usmaa\.julia\packages\Plots\FCM0H\src\utils.jl:294

juliohm · December 16, 2021, 1:04pm

Please share the exact code you tried to run and quote it in backquotes so that Discourse highlights it correctly.

usman0311 · December 16, 2021, 1:06pm

I am using the following code (Julia 1.7.0).

using DataFrames, Plots, DelimitedFiles, Glob, LaTeXStrings

f=Glob.glob("*.txt")

df=readdlm(f[1],comment_char='#',comments=true)
df=DataFrame(df,:auto)

Chi,phi,I=df[:,1],df[:,2],df[:,3]

pyplot()

c=heatmap(Chi,phi,I,fill=true,c=:Spectral,frame=:box,proj=:polar,xlabel=L"$\chi$",ylabel=L"$\phi$", width=1000, height=1000)
savefig(c,"pole122.png")

It uses my data file , how do I share it

juliohm · December 16, 2021, 1:17pm

Ideally you don’t need to share a file, just create fake data and make a minimum working example. That way we can easily help without downloading data.

rafael.guerra · December 16, 2021, 3:45pm

Plots.jl pyplot() backend works (see example here) but with some limitations and PyPlot.jl seems to work best (see github post here).

PyPlot example below:

using PyPlot
fig = plt.figure()
ax = fig.add_subplot(111, projection="polar")
ρ = LinRange(0., 7, 200)
θ = LinRange(0., 2π, 360)
funp(ρ,θ) =  sin(2ρ) * cos(θ)
pc = pcolormesh(θ, ρ, funp.(ρ,θ'))
cbar = plt.colorbar(pc)
cbar.set_label("Intensity")
ax[:grid](true)

usman0311 · December 16, 2021, 5:39pm

Thanks a lot, Rafael it works

jheinen · December 18, 2021, 1:25am

Also works in GR:

using GR
ρ = LinRange(0., 7, 200)
θ = LinRange(0., 2π, 360)
funp(ρ,θ) =  sin(2ρ) * cos(θ)
polarheatmap(funp.(ρ,θ'))

usman0311 · December 18, 2021, 4:24am

Thanks, Jheinen. This solution also works, but how could one change other plot properties like color and levels

rafael.guerra · December 18, 2021, 6:02am

@jheinen, what do the labels 100.5 and 0.5 mean?

jheinen · December 18, 2021, 7:30am

Those labels are derived from the ρ range. It’s a bug

rafael.guerra · December 18, 2021, 8:13am

Don’t you have to specify the polar coordinates here in order to get the correct ranges? See above how the similar PyPlot function was called.

jheinen · December 18, 2021, 9:10am

Thanks for the hint. I will change the heatmap functions next week.

jheinen · February 11, 2022, 11:31pm

I think that’s fixed in the meantime:

using GR
ρ = LinRange(0., 7, 200)
θ = LinRange(0., 2π, 360)
funp(ρ,θ) =  sin(2ρ) * cos(θ)
polarheatmap(ρ,θ,funp.(ρ,θ')')