feat(ggplot2): implement hexbin-map-geographic (#7750)

## Implementation: `hexbin-map-geographic` - r/ggplot2

Implements the **r/ggplot2** version of `hexbin-map-geographic`.

**File:** `plots/hexbin-map-geographic/implementations/r/ggplot2.R`

**Parent Issue:** #3767

---
:robot: *[impl-generate
workflow](https://github.com/MarkusNeusinger/anyplot/actions/runs/26514087663)*

---------

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: Markus Neusinger <2921697+MarkusNeusinger@users.noreply.github.com>

Author: github-actions[bot]

plots/hexbin-map-geographic/implementations/r/ggplot2.R

@@ -0,0 +1,181 @@
+#' anyplot.ai
+#' hexbin-map-geographic: Hexagonal Binning Map
+#' Library: ggplot2 3.5.1 | R 4.4.1
+#' Quality: 89/100 | Created: 2026-05-27
+
+library(ggplot2)
+library(dplyr)
+library(tibble)
+library(scales)
+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"
+MAP_WATER   <- if (THEME == "light") "#C8DCE8" else "#1A2530"
+MAP_LAND    <- if (THEME == "light") "#E6E0D4" else "#2C2A22"
+MAP_BORDER  <- if (THEME == "light") "#9A9890" else "#58584E"
+
+# NYC metro area taxi pickups — simulated density clusters
+# Centres: Midtown, Greenwich Village, UWS, Chelsea, S.Brooklyn,
+#          Midtown East, Lower Manhattan, JFK-adjacent, LGA-adjacent, Jersey City
+cluster_centers <- tibble::tibble(
+  lat   = c(40.756, 40.730, 40.775, 40.744, 40.676,
+             40.762, 40.710, 40.645, 40.769, 40.727),
+  lon   = c(-73.989, -74.003, -73.981, -73.995, -73.982,
+             -73.971, -73.997, -73.794, -73.863, -74.077),
+  n     = c(5000L, 3200L, 2400L, 2600L, 1800L,
+             1400L, 1000L, 700L, 600L, 500L),
+  s_lat = c(0.010, 0.009, 0.011, 0.009, 0.013,
+             0.010, 0.009, 0.009, 0.008, 0.009),
+  s_lon = c(0.013, 0.011, 0.013, 0.011, 0.015,
+             0.012, 0.011, 0.012, 0.010, 0.011)
+)
+
+pickups <- dplyr::bind_rows(
+  lapply(seq_len(nrow(cluster_centers)), function(i) {
+    cc <- cluster_centers[i, ]
+    tibble::tibble(
+      lat = rnorm(cc$n, cc$lat, cc$s_lat),
+      lon = rnorm(cc$n, cc$lon, cc$s_lon)
+    )
+  })
+) |> dplyr::filter(
+  lat >= 40.60, lat <= 40.83,
+  lon >= -74.15, lon <= -73.75
+)
+
+# --- Simplified NYC geographic context (hand-digitized approximate outlines) ---
+# sf/rnaturalearth not available; inline polygons provide coastline context.
+# Water shows as panel background (MAP_WATER).
+
+# New Jersey — land mass west of the Hudson River
+nj_land <- tibble::tibble(
+  group = "nj",
+  lon   = c(-74.15, -74.15, -73.960, -73.980, -74.015, -74.034, -74.050,
+            -74.085, -74.115, -74.15),
+  lat   = c(40.60,  40.83,  40.830,  40.800,  40.765,  40.725,  40.700,
+            40.660,  40.630,  40.60)
+)
+
+# Manhattan Island — narrow north-south strip between Hudson and East River.
+# Points trace the eastern shoreline (Battery → Harlem) then west (Harlem → Battery).
+manhattan_land <- tibble::tibble(
+  group = "manhattan",
+  lon   = c(
+    # East shore: south to north
+    -73.971, -73.972, -73.975, -73.971, -73.965, -73.952, -73.940, -73.928,
+    # North clip at lat 40.830 (Inwood not in view)
+    -73.934, -73.943,
+    # West shore: north to south
+    -73.955, -73.965, -73.973, -73.982, -73.991, -74.001, -74.010, -74.014, -73.971
+  ),
+  lat   = c(
+    40.700, 40.725, 40.742, 40.758, 40.764, 40.788, 40.808, 40.830,
+    40.830, 40.822,
+    40.813, 40.800, 40.782, 40.764, 40.749, 40.732, 40.715, 40.703, 40.700
+  )
+)
+
+# Brooklyn and Queens — southeastern land mass south of the East River
+bq_land <- tibble::tibble(
+  group = "bq",
+  lon   = c(-74.030, -73.993, -73.975, -73.960, -73.938, -73.880, -73.800,
+            -73.75,  -73.75,  -74.030),
+  lat   = c(40.700,  40.698,  40.684,  40.672,  40.665,  40.651,  40.636,
+            40.628,  40.60,   40.60)
+)
+
+nyc_geo <- dplyr::bind_rows(nj_land, manhattan_land, bq_land)
+
+# --- Plot ---
+
+plot_title <- "hexbin-map-geographic · r · ggplot2 · anyplot.ai"
+title_size <- max(8L, round(12 * min(1.0, 67 / nchar(plot_title))))
+
+p <- ggplot() +
+  # Geographic base map
+  geom_polygon(
+    data      = nyc_geo,
+    aes(x = lon, y = lat, group = group),
+    fill      = MAP_LAND,
+    color     = MAP_BORDER,
+    linewidth = 0.30
+  ) +
+  # Hexbin density layer
+  geom_hex(
+    data  = pickups,
+    aes(x = lon, y = lat),
+    bins  = 38,
+    alpha = 0.88
+  ) +
+  # Storytelling annotation: point to primary hotspot
+  annotate("segment",
+    x = -73.975, xend = -73.989,
+    y = 40.773,  yend = 40.762,
+    color = INK, linewidth = 0.45,
+    arrow = arrow(length = unit(0.18, "cm"), type = "closed")
+  ) +
+  annotate("text",
+    x = -73.968, y = 40.776,
+    label    = "Midtown hotspot",
+    color    = INK,
+    size     = 2.7,
+    fontface = "italic",
+    hjust    = 0
+  ) +
+  scale_fill_gradient(
+    low    = "#009E73",
+    high   = "#4467A3",
+    name   = "Pickup\nCount",
+    labels = scales::comma,
+    guide  = guide_colorbar(barwidth = 0.8, barheight = 8)
+  ) +
+  scale_x_continuous(
+    labels = function(x) sprintf("%.2f°W", -x),
+    expand = expansion(mult = 0.0)
+  ) +
+  scale_y_continuous(
+    labels = function(y) sprintf("%.2f°N", y),
+    expand = expansion(mult = 0.0)
+  ) +
+  coord_fixed(
+    ratio = 1,
+    xlim  = c(-74.15, -73.75),
+    ylim  = c(40.60, 40.83)
+  ) +
+  labs(
+    x     = "Longitude",
+    y     = "Latitude",
+    title = plot_title
+  ) +
+  theme_minimal(base_size = 8) +
+  theme(
+    plot.background   = element_rect(fill = PAGE_BG, color = PAGE_BG),
+    panel.background  = element_rect(fill = MAP_WATER, color = NA),
+    panel.grid.major  = element_line(color = INK_SOFT, linewidth = 0.10),
+    panel.grid.minor  = 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 = title_size, face = "bold"),
+    legend.background = element_rect(fill = ELEVATED_BG, color = INK_SOFT, linewidth = 0.3),
+    legend.text       = element_text(color = INK_SOFT, size = 8),
+    legend.title      = element_text(color = INK,      size = 9),
+    legend.position   = "right",
+    plot.margin       = margin(0.4, 0.4, 0.4, 0.4, "cm")
+  )
+
+ggsave(
+  filename = sprintf("plot-%s.png", THEME),
+  plot     = p,
+  device   = ragg::agg_png,
+  width    = 8,
+  height   = 4.5,
+  units    = "in",
+  dpi      = 400
+)