feat(ggplot2): implement area-elevation-profile

plots/area-elevation-profile/implementations/r/ggplot2.R

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+#' anyplot.ai
+#' area-elevation-profile: Terrain Elevation Profile Along Transect
+#' Library: ggplot2 3.5.1 | R 4.4.1
+#' Quality: 88/100 | Created: 2026-06-10
+
+library(ggplot2)
+library(scales)
+library(ragg)
+library(grid)
+
+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"
+INK_MUTED   <- if (THEME == "light") "#6B6A63" else "#A8A79F"
+IMPRINT_PALETTE <- c(
+  "#009E73", "#C475FD", "#4467A3", "#BD8233",
+  "#AE3030", "#2ABCCD", "#954477", "#99B314"
+)
+
+# --- Data -------------------------------------------------------------------
+# Alpine traverse: 120 km transect, sampled every 250 m (481 points)
+ctrl_km  <- c(0,    8,    18,   25,   30,   38,   45,   52,   60,   70,   78,   90,  105, 120)
+ctrl_elv <- c(820, 1100, 1870, 2420, 2650, 2000, 2120, 1750, 2470, 2200, 2980, 1950, 1300, 1080)
+
+sfn      <- splinefun(ctrl_km, ctrl_elv, method = "natural")
+distance <- seq(0, 120, by = 0.25)
+noise    <- cumsum(rnorm(length(distance), 0, 3)) * 0.25
+elevation <- pmax(sfn(distance) + noise, 750)
+
+trail <- data.frame(distance = distance, elevation = elevation)
+
+# Valley floor for ribbon base — matches the actual data minimum
+elev_floor <- min(elevation)
+
+# Key landmarks — elevation matched to the noisy profile
+lm_dist <- c(0, 18, 30, 45, 60, 78, 120)
+lm_name <- c("Valley Start", "Fontaine Col", "Aiguille Peak",
+             "Lac Hut", "Grand Col", "High Summit", "Valley End")
+lm_elev <- approx(trail$distance, trail$elevation, xout = lm_dist)$y
+
+landmarks <- data.frame(
+  name      = lm_name,
+  distance  = lm_dist,
+  elevation = lm_elev,
+  lbl_hjust = c(0, 0, 0, 0, 0, 0, 1),
+  label     = paste0(lm_name, " (", round(lm_elev), "m)")
+)
+
+# --- Title / sizing ---------------------------------------------------------
+TITLE      <- "area-elevation-profile · r · ggplot2 · anyplot.ai"
+title_size <- max(round(12 * min(1, 67 / nchar(TITLE))), 8)
+
+# --- Gradient terrain fill (ggplot2 >= 3.5.0) --------------------------------
+# Gradient from muted deep green at valley floor to bright brand green at peaks
+terrain_fill <- linearGradient(
+  colours = c(scales::alpha("#006B4F", 0.40), scales::alpha("#009E73", 0.65)),
+  y1 = unit(0, "npc"), y2 = unit(1, "npc")
+)
+
+# --- Plot -------------------------------------------------------------------
+p <- ggplot(trail, aes(x = distance)) +
+  # Terrain silhouette — gradient fill from valley floor to profile
+  geom_ribbon(
+    aes(ymin = elev_floor, ymax = elevation),
+    fill = terrain_fill, color = NA
+  ) +
+  # Profile line
+  geom_line(
+    aes(y = elevation),
+    color = IMPRINT_PALETTE[1], linewidth = 1.0
+  ) +
+  # Landmark dashed verticals
+  geom_vline(
+    data = landmarks, aes(xintercept = distance),
+    color = INK_SOFT, linewidth = 0.4, linetype = "dashed"
+  ) +
+  # Landmark dots (open circle, page-bg fill for definition)
+  geom_point(
+    data = landmarks, aes(x = distance, y = elevation),
+    shape = 21, size = 2.5,
+    color = IMPRINT_PALETTE[1], fill = PAGE_BG, stroke = 1.2
+  ) +
+  # Landmark labels with name and elevation at 45° angle
+  geom_text(
+    data = landmarks,
+    aes(x = distance, y = elevation + 160, label = label, hjust = lbl_hjust),
+    color = INK, size = 3.0, vjust = 0, angle = 45
+  ) +
+  labs(
+    title    = TITLE,
+    subtitle = "Alpine Traverse · 120 km · ~10× vertical exaggeration",
+    x        = "Distance (km)",
+    y        = "Elevation (m)"
+  ) +
+  scale_x_continuous(
+    breaks = seq(0, 120, 20),
+    expand = expansion(mult = c(0.02, 0.04))
+  ) +
+  scale_y_continuous(
+    breaks = seq(800, 3200, 200),
+    labels = scales::comma
+  ) +
+  coord_cartesian(ylim = c(elev_floor, 3500)) +
+  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.y = element_line(color = INK_SOFT, linewidth = 0.2),
+    panel.grid.major.x = element_blank(),
+    panel.grid.minor   = element_blank(),
+    panel.border       = element_blank(),
+    axis.title         = element_text(color = INK, size = 10),
+    axis.text          = element_text(color = INK_SOFT, size = 8),
+    axis.line.x        = element_line(color = INK_SOFT, linewidth = 0.4),
+    axis.line.y        = element_line(color = INK_SOFT, linewidth = 0.4),
+    axis.ticks.x       = element_line(color = INK_SOFT, linewidth = 0.3),
+    axis.ticks.y       = element_blank(),
+    plot.title         = element_text(color = INK, size = title_size, hjust = 0.5),
+    plot.subtitle      = element_text(color = INK_SOFT, size = 8, hjust = 0.5),
+    plot.margin        = margin(20, 30, 15, 15, "pt")
+  )
+
+# --- Save -------------------------------------------------------------------
+ggsave(
+  filename = sprintf("plot-%s.png", THEME),
+  plot     = p,
+  device   = ragg::agg_png,
+  width    = 8,
+  height   = 4.5,
+  units    = "in",
+  dpi      = 400
+)