Stacked area plots in Makie

Specific Domains Visualization
1

This seems like a very simple question, but what is the easiest way to create a stacked area plot in Makie? I can’t seem to find that in the (very good) tutorials and documentation.

A short example in PlotlyJS:

using PlotlyJS
x = collect(0:10)
y1 = x
y2 = ones(size(x))
t1 = scatter(x=x, y=y1, stackgroup="one")
t2 = scatter(x=x, y=y2, stackgroup="one")
plot([t1, t2])

I understand I can get to the same result by using band in Makie and stacking the values myself, but I am probably missing an easier way to achieve that.

1 Like
3

Sorry, thought you meant something else earlier haha.

do you mean this sort of thing? no idea the best way to do it, chatgpt spit this out…which is not really any better than just using band like you said

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# Sample data
x = 1:12  # Represents months
y1 = [10, 12, 15, 20, 18, 25, 30, 28, 35, 40, 38, 42]  # Category 1
y2 = [5, 8, 10, 12, 14, 15, 18, 20, 23, 25, 28, 30]   # Category 2
y3 = [3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25]     # Category 3

# Stack the data
y_stack = [y1 y2 y3]
y_cumulative = cumsum(y_stack, dims=2)

# Plotting
fig = Figure()
ax = Axis(fig[1, 1], title="Stacked Area Plot")

for i in 1:size(y_stack, 2)
    if i == 1
        fill_between!(ax, x, 0, y_cumulative[:, i], label="y$i")
    else
        fill_between!(ax, x, y_cumulative[:, i-1], y_cumulative[:, i], label="y$i")
    end
end

fig
4

Thanks, I think it’s a bit better than band, but far from convenient.
It seems strange to me, in other plotting packages it’s usually easy to get a stacked area plot.

5

Just as an add-on, I was surprised that ChatGPT would be able to find a solution which, while not being perfect, seems to be a good workaround. So I tried myself (not familiar with the tool, just went to the website and wrote “write julia code to draw a stacked area chart in makie”.
This is what it gave (reformatted for the forum)

using Pkg
Pkg.add("Makie")
using Makie
# Sample data
x = 1:10
y1 = [2, 3, 4, 5, 4, 3, 2, 3, 4, 5]
y2 = [1, 2, 1, 2, 3, 4, 3, 2, 1, 2]
y3 = [3, 2, 4, 3, 2, 3, 4, 5, 4, 3]
# Create a figure
fig = Figure()
# Create an axis
ax = Axis(fig[1, 1])
# Plot the stacked area chart
stacked_area!(ax, x, [y1, y2, y3], stack=true)
# Set labels and title
ax.xlabel = "X-axis"
ax.ylabel = "Y-axis"
ax.title = "Stacked Area Chart"
# Show the figure
display(fig)

I like the stacked_area! function, except it doesn’t seem to exist in CairoMakie nor GLMakie…
Oh well, I am almost glad ChatGPT didn’t know the answer…

6

I think my chatgpt got lucky with fill_between! because it’s a matplotlib function haha. It’s probably better to use band since fill_between! doesn’t actually appear in the docs anywhere

function stacked_area_plot!(ax, x, ys)
    y_stack = reduce(hcat, ys)
    y_cumulative = cumsum(y_stack, dims=2)

    for i in 1:size(y_stack, 2)
        if i == 1
            band!(ax, x, zeros(length(x)), y_cumulative[:, i], label="Category $i")
        else
            band!(ax, x, y_cumulative[:, i-1], y_cumulative[:, i], label="Category $i")
        end
    end
    
    nothing
end
 
f = Figure()
ax = Axis(f[1, 1])

x = 1:12  
y1 = [10, 12, 15, 20, 18, 25, 30, 28, 35, 40, 38, 42] 
y2 = [5, 8, 10, 12, 14, 15, 18, 20, 23, 25, 28, 30]   
y3 = [3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25] 

ys = [y1, y2, y3]

stacked_area_plot!(ax, x, ys)
f
7

Yes that’s a good point. I said in my original post that I liked the Makie documentation, but I was a bit frustrated to find nothing on fill_between!.
I will mark your most recent answer as the solution, thanks!

8

We should probably create a stackedarea recipe for this…it shouldn’t be too hard though!