A grid of scatter plots showing all pairwise relationships between multiple variables, with histograms or kernel density estimates on the diagonal. This comprehensive visualization enables simultaneous exploration of correlations and distributions across an entire dataset, making it invaluable for understanding multivariate data structure at a glance. Also known as a pairplot or SPLOM (Scatter Plot Matrix).
# anyplot.ai
# scatter-matrix: Scatter Plot Matrix
# Library: makie 0.21.9 | Julia 1.11.9
# Quality: 91/100 | Created: 2026-09-09
using CairoMakie
using Colors
using RDatasets
using Random
using Statistics
Random.seed!(42)
# --- Theme tokens -------------------------------------------------------
THEME = get(ENV, "ANYPLOT_THEME", "light")
PAGE_BG = THEME == "light" ? colorant"#FAF8F1" : colorant"#1A1A17"
ELEVATED_BG = THEME == "light" ? colorant"#FFFDF6" : colorant"#242420"
INK = THEME == "light" ? colorant"#1A1A17" : colorant"#F0EFE8"
INK_SOFT = THEME == "light" ? colorant"#4A4A44" : colorant"#B8B7B0"
GRID_COLOR = RGBAf(INK.r, INK.g, INK.b, 0.15)
IMPRINT_PALETTE = [
colorant"#009E73", colorant"#C475FD", colorant"#4467A3", colorant"#BD8233",
colorant"#AE3030", colorant"#2ABCCD", colorant"#954477", colorant"#99B314",
]
# --- Data -----------------------------------------------------------------
iris = dataset("datasets", "iris")
variables = [:SepalLength, :SepalWidth, :PetalLength, :PetalWidth]
var_labels = ["Sepal Length", "Sepal Width", "Petal Length", "Petal Width"]
n_vars = length(variables)
species_names = unique(iris.Species)
species_colors = Dict(sp => IMPRINT_PALETTE[i] for (i, sp) in enumerate(species_names))
point_colors = [species_colors[sp] for sp in iris.Species]
# Locate the most strongly correlated pair of variables to draw the eye
# toward a focal insight, rather than treating every panel identically.
cor_matrix = [cor(iris[!, variables[i]], iris[!, variables[j]]) for i in 1:n_vars, j in 1:n_vars]
best_row, best_col, best_r = 1, 2, 0.0
for i in 1:n_vars, j in 1:n_vars
if i != j && abs(cor_matrix[i, j]) > best_r
global best_row, best_col, best_r = i, j, abs(cor_matrix[i, j])
end
end
# --- Plot -------------------------------------------------------------------
title_str = "scatter-matrix · julia · makie · anyplot.ai"
fig = Figure(
resolution = (1200, 1200),
fontsize = 14,
backgroundcolor = PAGE_BG,
)
Label(fig[1, 1:(n_vars + 1)], title_str; fontsize = 20, color = INK, font = :bold)
axes = Matrix{Axis}(undef, n_vars, n_vars)
for row in 1:n_vars, col in 1:n_vars
is_diag = row == col
is_focal = !is_diag && (row, col) in ((best_row, best_col), (best_col, best_row))
show_y = col == 1 && !is_diag
show_x = row == n_vars
spine_color = is_focal ? IMPRINT_PALETTE[1] : INK_SOFT
ax = Axis(
fig[row + 1, col];
backgroundcolor = PAGE_BG,
xlabel = var_labels[col],
ylabel = var_labels[row],
xlabelsize = 13,
ylabelsize = 13,
xlabelcolor = INK,
ylabelcolor = INK,
xlabelvisible = show_x,
ylabelvisible = show_y,
xticklabelsize = 10,
yticklabelsize = 10,
xticklabelcolor = INK_SOFT,
yticklabelcolor = INK_SOFT,
xticklabelsvisible = show_x,
yticklabelsvisible = show_y,
xticksvisible = show_x,
yticksvisible = show_y,
xtickcolor = INK_SOFT,
ytickcolor = INK_SOFT,
leftspinecolor = spine_color,
bottomspinecolor = spine_color,
topspinevisible = is_focal,
rightspinevisible = is_focal,
topspinecolor = spine_color,
rightspinecolor = spine_color,
spinewidth = is_focal ? 2.5 : 1,
xgridcolor = GRID_COLOR,
ygridcolor = GRID_COLOR,
xminorgridvisible = false,
yminorgridvisible = false,
)
axes[row, col] = ax
if is_diag
ax.yticklabelsvisible = false
ax.ylabelvisible = false
ax.yticksvisible = false
for sp in species_names
vals = iris[iris.Species .== sp, variables[row]]
density!(
ax, vals;
color = (species_colors[sp], 0.35),
strokecolor = species_colors[sp],
strokewidth = 2,
)
end
else
scatter!(
ax, iris[!, variables[col]], iris[!, variables[row]];
color = point_colors,
alpha = 0.6,
markersize = 7,
strokewidth = 0,
)
if is_focal
text!(
ax, 0.05, 0.95;
text = "r = $(round(best_r, digits = 2))",
space = :relative,
align = (:left, :top),
color = IMPRINT_PALETTE[1],
fontsize = 12,
font = :bold,
)
end
end
end
# Distinctive Makie SPLOM idiom: explicitly guarantee identical per-column /
# per-row ranges instead of relying on each Axis picking its own limits.
for col in 1:n_vars
linkxaxes!(axes[:, col]...)
end
for row in 1:n_vars
off_diag_in_row = [axes[row, col] for col in 1:n_vars if col != row]
linkyaxes!(off_diag_in_row...)
end
legend_elements = [MarkerElement(color = species_colors[sp], marker = :circle, markersize = 14) for sp in species_names]
Legend(
fig[2:(n_vars + 1), n_vars + 1],
legend_elements, string.(species_names), "Species";
labelcolor = INK,
titlecolor = INK,
backgroundcolor = ELEVATED_BG,
framevisible = false,
)
colgap!(fig.layout, 8)
rowgap!(fig.layout, 8)
# --- Save -------------------------------------------------------------------
save("plot-$(THEME).png", fig; px_per_unit = 2)
Runnable source as JSON, for any HTTP client: https://api.anyplot.ai/specs/scatter-matrix/makie/code. Any spec id and library id listed in llms-full.txt fit the same URL shape; every URL below is complete and callable.
{
"spec_id": "scatter-matrix",
"language": "julia",
"library": "makie",
"page": "https://anyplot.ai/scatter-matrix/julia/makie",
"hub": "https://anyplot.ai/scatter-matrix",
"code_json": "https://api.anyplot.ai/specs/scatter-matrix/makie/code",
"spec_json": "https://api.anyplot.ai/specs/scatter-matrix",
"render_light_png": "https://storage.googleapis.com/anyplot-images/plots/scatter-matrix/julia/makie/plot-light.png",
"render_dark_png": "https://storage.googleapis.com/anyplot-images/plots/scatter-matrix/julia/makie/plot-dark.png",
"quality_score": 91.0,
"license": "MIT",
"guide": "https://anyplot.ai/llms.txt"
}Part of Scatter Plot Matrix on anyplot.ai.