A scatter plot with a LOWESS (Locally Weighted Scatterplot Smoothing) regression curve overlaid. LOWESS is a non-parametric method that fits smooth curves by performing local weighted regressions at each point, adapting to local data patterns without assuming a specific functional form. This makes it ideal for exploring complex relationships where the underlying pattern is unknown or varies across the data range.
#' anyplot.ai
#' scatter-regression-lowess: Scatter Plot with LOWESS Regression
#' Library: ggplot2 3.5.1 | R 4.4.1
#' Quality: 90/100 | Created: 2026-09-09
library(ggplot2)
library(ragg)
set.seed(42)
# --- Theme tokens -------------------------------------------------------
THEME <- Sys.getenv("ANYPLOT_THEME", "light")
PAGE_BG <- if (THEME == "light") "#FAF8F1" else "#1A1A17"
ELEVATED_BG <- if (THEME == "light") "#FFFDF6" else "#242420"
INK <- if (THEME == "light") "#1A1A17" else "#F0EFE8"
INK_SOFT <- if (THEME == "light") "#4A4A44" else "#B8B7B0"
IMPRINT_PALETTE <- c(
"#009E73", "#C475FD", "#4467A3", "#BD8233",
"#AE3030", "#2ABCCD", "#954477", "#99B314"
)
BRAND <- IMPRINT_PALETTE[1]
# ggplot2 doesn't expose an alpha channel for grid-line color directly, so
# fade the grid by blending INK toward PAGE_BG instead of using full-opacity
# ink (keeps gridlines subtle behind the scatter/LOWESS curve).
blend_toward_bg <- function(fg, bg, amount) {
mixed <- col2rgb(fg) * amount + col2rgb(bg) * (1 - amount)
rgb(mixed[1, ], mixed[2, ], mixed[3, ], maxColorValue = 255)
}
GRID_COLOR <- blend_toward_bg(INK, PAGE_BG, 0.2)
# --- Data ----------------------------------------------------------------
# Enzyme activity across a temperature range: activity rises as the enzyme
# warms toward its optimum, then collapses once heat denatures the protein.
# This non-monotonic dose-response curve is exactly the case LOWESS is built
# for, since a single polynomial or linear fit cannot follow the rise-then-
# fall shape.
n <- 220
temperature_c <- runif(n, 10, 70)
optimum <- 42
true_activity <- 100 * exp(-((temperature_c - optimum)^2) / (2 * 11^2))
enzyme_activity <- pmax(0, true_activity + rnorm(n, mean = 0, sd = 9))
df <- tibble::tibble(
temperature_c = temperature_c,
enzyme_activity = enzyme_activity
)
# --- Plot ------------------------------------------------------------------
p <- ggplot(df, aes(x = temperature_c, y = enzyme_activity)) +
geom_point(color = BRAND, size = 2.5, alpha = 0.55) +
geom_smooth(
method = "loess", span = 0.4, se = TRUE,
color = IMPRINT_PALETTE[2], fill = IMPRINT_PALETTE[2],
linewidth = 1.1, alpha = 0.18
) +
labs(
title = "scatter-regression-lowess · r · ggplot2 · anyplot.ai",
x = "Incubation Temperature (°C)",
y = "Enzyme Activity (% of maximum)"
) +
theme_minimal(base_size = 8) +
theme(
plot.background = element_rect(fill = PAGE_BG, color = PAGE_BG),
panel.background = element_rect(fill = PAGE_BG, color = NA),
panel.grid.major = element_line(color = GRID_COLOR, linewidth = 0.3),
panel.grid.minor = element_line(color = GRID_COLOR, linewidth = 0.2),
axis.line.x.bottom = element_line(color = INK_SOFT),
axis.line.x.top = element_blank(),
axis.line.y.left = element_line(color = INK_SOFT),
axis.line.y.right = element_blank(),
axis.title = element_text(color = INK, size = 10),
axis.text = element_text(color = INK_SOFT, size = 8),
plot.title = element_text(color = INK, size = 12)
)
# --- Save --------------------------------------------------------------
ggsave(
filename = sprintf("plot-%s.png", THEME),
plot = p,
device = ragg::agg_png,
width = 8,
height = 4.5,
units = "in",
dpi = 400
)
Runnable source as JSON, for any HTTP client: https://api.anyplot.ai/specs/scatter-regression-lowess/ggplot2/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-regression-lowess",
"language": "r",
"library": "ggplot2",
"page": "https://anyplot.ai/scatter-regression-lowess/r/ggplot2",
"hub": "https://anyplot.ai/scatter-regression-lowess",
"code_json": "https://api.anyplot.ai/specs/scatter-regression-lowess/ggplot2/code",
"spec_json": "https://api.anyplot.ai/specs/scatter-regression-lowess",
"render_light_png": "https://storage.googleapis.com/anyplot-images/plots/scatter-regression-lowess/r/ggplot2/plot-light.png",
"render_dark_png": "https://storage.googleapis.com/anyplot-images/plots/scatter-regression-lowess/r/ggplot2/plot-dark.png",
"quality_score": 90.0,
"license": "MIT",
"guide": "https://anyplot.ai/llms.txt"
}Part of Scatter Plot with LOWESS Regression on anyplot.ai.