An arc diagram arranges nodes along a single horizontal line and draws connections between them as curved arcs above the line. This layout excels at revealing patterns in sequential or ordered data while minimizing visual clutter compared to force-directed layouts. Arc height typically indicates the distance between connected nodes, making it easy to spot long-range versus short-range connections.
#' anyplot.ai
#' arc-basic: Basic Arc Diagram
#' Library: ggplot2 3.5.1 | R 4.4.1
#' Quality: 83/100 | Created: 2026-05-30
library(ggplot2)
library(dplyr)
library(tibble)
library(tidyr)
library(ragg)
set.seed(42)
# Theme tokens (Imprint palette)
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")
# Nodes: Hamlet characters ordered by narrative prominence
node_names <- c("Hamlet", "Horatio", "Claudius", "Gertrude", "Ophelia",
"Polonius", "Laertes", "Marcellus", "Rosencrantz", "Guildenstern")
node_df <- tibble(name = node_names, x = seq_along(node_names))
# Edges with relationship type
edges_df <- tribble(
~from, ~to, ~type,
"Hamlet", "Horatio", "Friendship",
"Hamlet", "Claudius", "Political",
"Hamlet", "Gertrude", "Family",
"Hamlet", "Ophelia", "Romantic",
"Hamlet", "Polonius", "Political",
"Hamlet", "Laertes", "Political",
"Hamlet", "Marcellus", "Friendship",
"Hamlet", "Rosencrantz", "Friendship",
"Hamlet", "Guildenstern", "Friendship",
"Claudius", "Gertrude", "Romantic",
"Claudius", "Polonius", "Political",
"Claudius", "Rosencrantz", "Political",
"Claudius", "Guildenstern", "Political",
"Ophelia", "Polonius", "Family",
"Ophelia", "Laertes", "Family",
"Polonius", "Laertes", "Family",
"Horatio", "Marcellus", "Friendship"
) %>%
left_join(node_df, by = c("from" = "name")) %>%
rename(x1 = x) %>%
left_join(node_df, by = c("to" = "name")) %>%
rename(x2 = x) %>%
mutate(edge_id = row_number())
# Semi-ellipse arcs: height proportional to span distance, inlined per-row
arc_data <- edges_df %>%
rowwise() %>%
mutate(pts = list({
cx <- (x1 + x2) / 2
r <- abs(x2 - x1) / 2
t <- seq(pi, 0, length.out = 80)
tibble(arc_x = cx + r * cos(t), arc_y = 0.55 * r * sin(t))
})) %>%
ungroup() %>%
unnest(cols = c(pts))
# Title: 36 chars < 67 baseline, so full default size
plot_title <- "arc-basic · r · ggplot2 · anyplot.ai"
n_chars <- nchar(plot_title)
title_size <- max(8L, round(12 * min(1.0, 67 / n_chars)))
# Relationship colors — Imprint palette positions 1–4
rel_colors <- c(
"Family" = IMPRINT_PALETTE[1], # #009E73 brand green
"Friendship" = IMPRINT_PALETTE[2], # #C475FD lavender
"Political" = IMPRINT_PALETTE[3], # #4467A3 blue
"Romantic" = IMPRINT_PALETTE[4] # #BD8233 ochre
)
p <- ggplot() +
# Arcs above the baseline
geom_path(
data = arc_data,
aes(x = arc_x, y = arc_y, group = edge_id, color = type),
linewidth = 0.85, alpha = 0.60
) +
# Horizontal baseline
geom_hline(yintercept = 0, color = INK_SOFT, linewidth = 0.35) +
# Nodes as filled circles on the baseline
geom_point(
data = node_df, aes(x = x, y = 0),
shape = 21, size = 3.0, fill = INK, color = PAGE_BG, stroke = 0.8
) +
# Node labels rotated below baseline
geom_text(
data = node_df, aes(x = x, y = -0.15, label = name),
color = INK_SOFT, size = 3.0, angle = 40, hjust = 1, vjust = 1
) +
scale_color_manual(values = rel_colors, name = "Relationship") +
scale_x_continuous(expand = expansion(mult = c(0.04, 0.12))) +
coord_cartesian(ylim = c(-0.8, 2.8), clip = "off") +
labs(title = plot_title) +
theme_void() +
theme(
plot.background = element_rect(fill = PAGE_BG, color = PAGE_BG),
panel.background = element_rect(fill = PAGE_BG, color = NA),
plot.title = element_text(color = INK, size = title_size,
hjust = 0.5, face = "bold",
margin = margin(t = 10, b = 6)),
legend.position = "bottom",
legend.direction = "horizontal",
legend.text = element_text(color = INK_SOFT, size = 8),
legend.title = element_text(color = INK, size = 9, face = "bold"),
legend.background = element_rect(fill = ELEVATED_BG, color = NA),
legend.key = element_rect(fill = NA, color = NA),
legend.margin = margin(2, 8, 4, 8),
plot.margin = margin(20, 20, 10, 20)
)
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/arc-basic/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": "arc-basic",
"language": "r",
"library": "ggplot2",
"page": "https://anyplot.ai/arc-basic/r/ggplot2",
"hub": "https://anyplot.ai/arc-basic",
"code_json": "https://api.anyplot.ai/specs/arc-basic/ggplot2/code",
"spec_json": "https://api.anyplot.ai/specs/arc-basic",
"render_light_png": "https://storage.googleapis.com/anyplot-images/plots/arc-basic/r/ggplot2/plot-light.png",
"render_dark_png": "https://storage.googleapis.com/anyplot-images/plots/arc-basic/r/ggplot2/plot-dark.png",
"quality_score": 83.0,
"license": "MIT",
"guide": "https://anyplot.ai/llms.txt"
}Part of Basic Arc Diagram on anyplot.ai.