Hello,
I have a matrix of floating numbers that I would like to plot as a grid whose cells are shaded according to these numbers. Thus, having
julia> grid = rand(Float32, 5, 5)
5×5 Matrix{Float32}:
0.157996 0.965474 0.869818 0.741637 0.621585
0.799489 0.944857 0.243435 0.0732432 0.928711
0.143084 0.755295 0.153082 0.45804 0.586859
0.896089 0.772248 0.631192 0.0818451 0.586762
0.689304 0.0514671 0.73454 0.567052 0.735969
I would like to get:
What would be the syntax?
Thank you
Oh, do you mean just like a heatmap?
Makie.jl: heatmap
Plots.jl: Heatmap, categorical axes, and aspect_ratio · Plots
2 Likes
Exactly! Thank you
using CairoMakie
xs = collect(range(1,stop=5))
ys = collect(range(1,stop=5))
zs = [cos(x) * sin(y) for x in xs, y in ys]
fig, ax, hm = heatmap(xs, ys, grid)
Colorbar(fig[:, end+1], hm)
Nice! CairoMakie is my favorite =]
In case you are interested in doing more stats-oriented plotting, AlgebraOfGraphics.jl is built-on top of Makie.jl and it gives you superpowers
1 Like
You might also like the aspect/Aspect keyword/object if you want the grid to be squares 
1 Like
Good point. I tried with
ax = Axis(fig[1, 1], ...aspect = 1)
but it came out rectangular…
using CairoMakie
using ColorSchemes
xs = collect(range(1,stop=5))
ys = collect(range(1,stop=5))
grid1 = rand(Float16, 5, 5)
grid2 = rand(Float16, 5, 5)
grid = grid1/grid2
fig, ax, hm = heatmap(xs, ys, grid, colormap = :bwr) # or :roma
ax = Axis(fig[1, 1], aspect = 1, xlabel = "X", ylabel = "Y",
title = "Title")
Colorbar(fig[:, end+1], hm)
save("heatmap.png", fig, px_per_unit = 2)
It looks like two plots have merged…
Yea, so I think there’s a couple things going on here. The merged look is coming from the two separate axes that are being set up (one from fig, ax, hm = ..., and the other from ax = Axis(...)), so I would just pick one and go with that. If we go with the first way, we can pass a special keyword arg
The other thing that I think is going on is that aspect = 1 will take care of the aspect ratio of the axis for us, but the figure will still need some special care to get right. There is a really nice way to do this that was recently added that I think @jacobusmmsmit was referring to, so I might try something like this:
xs = 1:5 # Don't think we need to collect here, a UnitRange should be fine
ys = 1:5
grid1 = rand(Float16, 5, 5)
grid2 = rand(Float16, 5, 5)
grid = grid1/grid2
fig, ax, hm = heatmap(xs, ys, grid;
axis = (xlabel="X", ylabel="Y"),
colormap = :bwr,
)
Colorbar(fig[:, end+1], hm)
colsize!(fig.layout, 1, Aspect(1, 1.0))
resize_to_layout!(fig)
fig
2 Likes
An addition: how can I show a grid (to facilitate the discrimination between cells of equal color)? Thanks
I think this was addressed here How to add grid lines on top of a heatmap in Makie? - #2 by jules
So basically just:
using CairoMakie
fig = Figure()
ax = Axis(fig[1, 1];
xgridcolor = :white,
xgridstyle = :dot,
xgridwidth = 10,
ygridcolor = :red,
ygridwidth = 10,
)
hm = heatmap!(ax, rand(5, 5))
translate!(hm, 0, 0, -100)
fig
A bunch more options can be found here API
I have seen that, but I am initializing fig, ax, hm in a single call. To me, the lines do not appear:
using CairoMakie
using ColorSchemes
xs = 1:11
ys = 1:11
grid1 = rand(Float16, 11, 11)
grid2 = rand(Float16, 11, 11)
grid = grid1/grid2
fig, ax, hm = heatmap(xs, ys, grid;
axis = (xlabel="X", ylabel="Y", xgridcolor = :black, ygridcolor = :black),
colormap = :bwr)
Colorbar(fig[:, end+1], hm)
colsize!(fig.layout, 1, Aspect(1, 1.0))
resize_to_layout!(fig)
save("heatmap.png", fig, px_per_unit = 2)
jules
12
You don’t have the line translate!(hm, 0, 0, -100), just add that after the heatmap call.
1 Like
