An epidemic curve (epi curve) is a histogram showing the number of new disease cases over time, plotted by date of symptom onset. The shape of the curve reveals the outbreak pattern: a sharp peak indicates a point source, successive waves suggest propagated transmission, and a plateau indicates continuous exposure. It is fundamental to epidemiological investigation and public health surveillance.
# anyplot.ai
# histogram-epidemic: Epidemic Curve (Epi Curve)
# Library: makie 0.22.10 | Julia 1.11.9
# Quality: 91/100 | Created: 2026-06-02
using CairoMakie
using Colors
using Random
using Dates
Random.seed!(42)
# Theme tokens
const THEME = get(ENV, "ANYPLOT_THEME", "light")
const PAGE_BG = THEME == "light" ? colorant"#FAF8F1" : colorant"#1A1A17"
const ELEVATED_BG = THEME == "light" ? colorant"#FFFDF6" : colorant"#242420"
const INK = THEME == "light" ? colorant"#1A1A17" : colorant"#F0EFE8"
const INK_SOFT = THEME == "light" ? colorant"#4A4A44" : colorant"#B8B7B0"
const INK_MUTED = THEME == "light" ? colorant"#6B6A63" : colorant"#A8A79F"
# Imprint palette — confirmed: pos 1 (brand green), probable: pos 2 (lavender)
const BRAND = colorant"#009E73"
const LAVENDER = colorant"#C475FD"
const AMBER = colorant"#DDCC77" # semantic anchor — intervention events
# Data — 90-day influenza-like outbreak, Oct–Dec 2023
n_days = 90
start_date = Date(2023, 10, 1)
wave1 = [180.0 * exp(-0.5 * ((d - 22)^2) / 72.0) for d in 1:n_days]
wave2 = [55.0 * exp(-0.5 * ((d - 62)^2) / 45.0) for d in 1:n_days]
noise = randn(n_days) .* 4.0
total_cases = max.(0, round.(Int, wave1 .+ wave2 .+ noise))
confirmed = round.(Int, total_cases .* 0.72)
probable = total_cases .- confirmed
cumulative = cumsum(total_cases)
max_daily = maximum(total_cases)
# Stacked barplot vectors (confirmed = stack 1 bottom, probable = stack 2 top)
x_stacked = vcat(1:n_days, 1:n_days)
y_stacked = vcat(Float64.(confirmed), Float64.(probable))
stack_groups = vcat(fill(1, n_days), fill(2, n_days))
bar_colors = vcat(fill(BRAND, n_days), fill(LAVENDER, n_days))
# X-axis ticks — fortnightly + endpoints
tick_positions = [1, 15, 30, 45, 60, 75, 90]
tick_labels = [Dates.format(start_date + Day(d - 1), "d u") for d in tick_positions]
# Intervention events (day, label)
interventions = [(25, "School closure"), (57, "Vaccination campaign")]
# Figure
fig = Figure(
size = (1600, 900),
fontsize = 14,
backgroundcolor = PAGE_BG,
)
# Primary axis: daily case counts (left y-axis)
ax = Axis(
fig[1, 1];
title = "histogram-epidemic · julia · makie · anyplot.ai",
titlesize = 20,
titlecolor = INK,
xlabel = "Date of symptom onset",
ylabel = "Daily new cases",
xlabelsize = 14,
ylabelsize = 14,
xlabelcolor = INK,
ylabelcolor = INK,
xticklabelsize = 11,
yticklabelsize = 11,
xticklabelcolor = INK_SOFT,
yticklabelcolor = INK_SOFT,
xtickcolor = INK_SOFT,
ytickcolor = INK_SOFT,
backgroundcolor = PAGE_BG,
topspinevisible = false,
rightspinevisible = false,
leftspinecolor = INK_SOFT,
bottomspinecolor = INK_SOFT,
xgridvisible = false,
ygridcolor = RGBAf(INK.r, INK.g, INK.b, 0.15),
xminorgridvisible = false,
yminorgridvisible = false,
xticks = (tick_positions, tick_labels),
xticklabelrotation = π / 6,
xticklabelalign = (:right, :center),
)
# Secondary axis: cumulative cases (right y-axis)
ax2 = Axis(
fig[1, 1];
yaxisposition = :right,
ylabel = "Cumulative cases",
ylabelsize = 14,
ylabelcolor = INK_MUTED,
yticklabelsize = 11,
yticklabelcolor = INK_MUTED,
ytickcolor = INK_MUTED,
rightspinecolor = INK_MUTED,
backgroundcolor = :transparent,
topspinevisible = false,
leftspinevisible = false,
bottomspinevisible = false,
xgridvisible = false,
ygridvisible = false,
xminorgridvisible = false,
yminorgridvisible = false,
)
hidexdecorations!(ax2)
linkxaxes!(ax, ax2)
# Stacked bars (epi curve histogram)
barplot!(ax, x_stacked, y_stacked;
stack = stack_groups,
color = bar_colors,
strokewidth = 0,
width = 1.0,
)
# Cumulative line on secondary axis
lines!(ax2, 1:n_days, Float64.(cumulative);
color = INK_MUTED,
linewidth = 2.0,
linestyle = :dash,
)
# Intervention events — vertical lines with labels
for (day, label) in interventions
vlines!(ax, [Float64(day)]; color = AMBER, linewidth = 1.5, linestyle = :dash)
text!(ax, day + 1, max_daily * 0.88;
text = label,
fontsize = 10,
color = AMBER,
align = (:left, :center),
)
end
# Axis limits
ylims!(ax, 0, nothing)
ylims!(ax2, 0, nothing)
xlims!(ax, 0.5, n_days + 0.5)
# Legend
legend_entries = [
PolyElement(color = BRAND, strokewidth = 0),
PolyElement(color = LAVENDER, strokewidth = 0),
LineElement(color = INK_MUTED, linewidth = 2.0, linestyle = :dash),
LineElement(color = AMBER, linewidth = 1.5, linestyle = :dash),
]
legend_labels = ["Confirmed", "Probable", "Cumulative cases", "Intervention"]
Legend(
fig[1, 2],
legend_entries,
legend_labels;
framecolor = INK_SOFT,
framevisible = true,
backgroundcolor = ELEVATED_BG,
labelsize = 11,
labelcolor = INK,
padding = (10, 10, 10, 10),
)
colsize!(fig.layout, 1, Relative(0.85))
# Save
save("plot-$(THEME).png", fig; px_per_unit = 2)
Runnable source as JSON, for any HTTP client: https://api.anyplot.ai/specs/histogram-epidemic/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": "histogram-epidemic",
"language": "julia",
"library": "makie",
"page": "https://anyplot.ai/histogram-epidemic/julia/makie",
"hub": "https://anyplot.ai/histogram-epidemic",
"code_json": "https://api.anyplot.ai/specs/histogram-epidemic/makie/code",
"spec_json": "https://api.anyplot.ai/specs/histogram-epidemic",
"render_light_png": "https://storage.googleapis.com/anyplot-images/plots/histogram-epidemic/julia/makie/plot-light.png",
"render_dark_png": "https://storage.googleapis.com/anyplot-images/plots/histogram-epidemic/julia/makie/plot-dark.png",
"quality_score": 91.0,
"license": "MIT",
"guide": "https://anyplot.ai/llms.txt"
}Part of Epidemic Curve (Epi Curve) on anyplot.ai.