Polar Heatmap for Cyclic Two-Dimensional Data — ggplot2

A heatmap wrapped around a circle where the angular axis represents a cyclic variable (e.g., hour of day, month) and the radial axis represents a second categorical or ordinal variable (e.g., day of week, year). Cell color encodes the measured value. This visualization reveals patterns in data with inherent cyclical structure that rectangular heatmaps distort, since the first and last angular bins are visually adjacent rather than separated at opposite ends of a row.

Polar Heatmap for Cyclic Two-Dimensional Data rendered with ggplot2

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R source (ggplot2)

#' anyplot.ai
#' heatmap-polar: Polar Heatmap for Cyclic Two-Dimensional Data
#' Library: ggplot2 3.5.1 | R 4.4.1
#' Quality: 89/100 | Created: 2026-09-05

library(ggplot2)
library(dplyr)
library(ragg)

set.seed(42)

# --- Theme tokens -------------------------------------------------------
THEME    <- Sys.getenv("ANYPLOT_THEME", "light")
PAGE_BG  <- if (THEME == "light") "#FAF8F1" else "#1A1A17"
INK      <- if (THEME == "light") "#1A1A17" else "#F0EFE8"
INK_SOFT <- if (THEME == "light") "#4A4A44" else "#B8B7B0"

# --- Data -----------------------------------------------------------------
# Hourly website visits, angular = hour of day (wraps continuously),
# radial = day of week (Monday innermost ring, Sunday outermost).
days  <- c("Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun")
hours <- 0:23

traffic <- expand.grid(day = days, hour = hours, stringsAsFactors = FALSE) %>%
  mutate(
    day_idx    = match(day, days),
    is_weekend = day %in% c("Sat", "Sun"),
    baseline   = ifelse(
      is_weekend,
      20 + 70 * exp(-(hour - 14)^2 / 30),
      40 + 90 * exp(-(hour - 8)^2 / 6) + 100 * exp(-(hour - 18)^2 / 8)
    ),
    visits     = pmax(0, baseline + rnorm(n(), mean = 0, sd = 8))
  )

# --- Plot -------------------------------------------------------------------
# Tiles are offset by +0.5h so cell edges land on whole hours (0-1, 1-2, ...);
# the y-axis leaves a hole below day_idx=1 so rings read outward from a
# center gap instead of overlapping at a point.
p <- ggplot(traffic, aes(x = hour + 0.5, y = day_idx, fill = visits)) +
  geom_tile(width = 1, height = 1, color = PAGE_BG, linewidth = 0.2) +
  coord_polar(theta = "x") +
  scale_x_continuous(
    limits = c(0, 24), expand = c(0, 0),
    breaks = c(0, 6, 12, 18), labels = c("12am", "6am", "12pm", "6pm")
  ) +
  scale_y_continuous(
    limits = c(-1.5, 7.5), expand = c(0, 0),
    breaks = 1:7, labels = days
  ) +
  scale_fill_gradient(low = "#009E73", high = "#4467A3", name = "Visits/hr") +
  labs(
    title    = "Hourly Website Traffic · heatmap-polar · r · ggplot2 · anyplot.ai",
    subtitle = "Hour of day (angular) · Day of week (radial)"
  ) +
  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 = INK_SOFT, linewidth = 0.15),
    panel.grid.minor  = element_blank(),
    axis.title        = element_blank(),
    axis.ticks        = element_blank(),
    axis.text.x       = element_text(color = INK_SOFT, size = 8),
    axis.text.y       = element_text(color = INK, size = 8, face = "bold"),
    plot.title        = element_text(color = INK, size = 12, hjust = 0.5),
    plot.subtitle     = element_text(color = INK_SOFT, size = 8, hjust = 0.5),
    legend.text       = element_text(color = INK_SOFT, size = 8),
    legend.title      = element_text(color = INK, size = 10),
    legend.background = element_rect(fill = PAGE_BG, color = NA)
  )

# --- Save -------------------------------------------------------------------
ggsave(
  filename = sprintf("plot-%s.png", THEME),
  plot     = p,
  device   = ragg::agg_png,
  width    = 6,
  height   = 6,
  units    = "in",
  dpi      = 400
)

Retrieve this implementation

Runnable source as JSON, for any HTTP client: https://api.anyplot.ai/specs/heatmap-polar/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": "heatmap-polar",
  "language": "r",
  "library": "ggplot2",
  "page": "https://anyplot.ai/heatmap-polar/r/ggplot2",
  "hub": "https://anyplot.ai/heatmap-polar",
  "code_json": "https://api.anyplot.ai/specs/heatmap-polar/ggplot2/code",
  "spec_json": "https://api.anyplot.ai/specs/heatmap-polar",
  "render_light_png": "https://storage.googleapis.com/anyplot-images/plots/heatmap-polar/r/ggplot2/plot-light.png",
  "render_dark_png": "https://storage.googleapis.com/anyplot-images/plots/heatmap-polar/r/ggplot2/plot-dark.png",
  "quality_score": 89.0,
  "license": "MIT",
  "guide": "https://anyplot.ai/llms.txt"
}

Part of Polar Heatmap for Cyclic Two-Dimensional Data on anyplot.ai.

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