def add_scale_bar(ax, provmap, location="bl",
height_scale=0.016, width_scale=0.2):
"""在地图左下角添加比例尺。"""
bounds = provmap.total_bounds
map_width_m = bounds[2] - bounds[0]
target_km = map_width_m * width_scale / 1000
nice_values = [500, 1000, 2000, 3000, 5000, 10000, 20000, 50000, 100000]
bar_km = min(nice_values, key=lambda x: abs(x - target_km))
bar_m = bar_km * 1000
x0_frac = 0.08 if location == "bl" else 0.62
xlim = ax.get_xlim()
ylim = ax.get_ylim()
ax_width = xlim[1] - xlim[0]
x0_data = xlim[0] + x0_frac * ax_width
y0_data = ylim[0] + 0.04 * (ylim[1] - ylim[0])
bar_height_m = map_width_m * height_scale
n_seg = 4
seg_w = bar_m / n_seg
for i in range(n_seg):
color = "black" if i % 2 == 0 else "white"
rect = Rectangle(
(x0_data + i * seg_w, y0_data), seg_w, bar_height_m,
facecolor=color, edgecolor="black", linewidth=0.5,
clip_on=False, zorder=10,
)
ax.add_patch(rect)
ax.text(x0_data + bar_m / 2, y0_data - bar_height_m * 0.3,
f"{bar_km:,} km", fontsize=7, ha="center", va="top",
color="black", zorder=10)
def add_north_arrow(ax):
"""在地图右上角添加指北针。"""
ax.annotate("N", xy=(0.98, 0.95), xycoords="axes fraction",
fontsize=10, fontweight="bold", ha="center", va="bottom")
ax.annotate("", xy=(0.98, 0.95), xycoords="axes fraction",
xytext=(0.98, 0.88), textcoords="axes fraction",
arrowprops=dict(arrowstyle="->", color="black", lw=1.5))
def draw_lines(ax, provlinemap):
"""绘制线条元素。"""
for _, row in provlinemap.iterrows():
cls = row["class"]
color = LINE_COLORS.get(cls, "gray")
lw = LINE_WIDTHS.get(cls, 0.3)
geom = row["geometry"]
if geom.geom_type == "MultiLineString":
for line in geom.geoms:
xs, ys = line.xy
ax.plot(xs, ys, color=color, linewidth=lw, zorder=3)
elif geom.geom_type == "LineString":
xs, ys = geom.xy
ax.plot(xs, ys, color=color, linewidth=lw, zorder=3)
def draw_province_labels(ax, provmap, centroids):
"""绘制省名标注。"""
for i, row in provmap.iterrows():
cx, cy = centroids.iloc[i].x, centroids.iloc[i].y
ax.text(cx, cy, row["省"], fontsize=5, color="gray",
ha="center", va="center", zorder=4)
def add_vertical_colorbar(ax, fig, cmap, norm, label=None,
ticks=None, ticklabels=None,
n_segments=4):
"""在地图左下角、比例尺上方绘制竖向分段色条。"""
xlim = ax.get_xlim()
ylim = ax.get_ylim()
ax_width = xlim[1] - xlim[0]
ax_height = ylim[1] - ylim[0]
cb_width_m = ax_width * 0.0075
cb_height_m = ax_height * 0.15
seg_height_m = cb_height_m / n_segments
x0_frac = 0.08
x0_data = xlim[0] + x0_frac * ax_width
scale_y0 = ylim[0] + 0.04 * ax_height
bar_height_m = ax_width * 0.016
cb_bottom = scale_y0 + bar_height_m + ax_height * 0.025
vmin, vmax = norm.vmin, norm.vmax
for i in range(n_segments):
frac_lo = i / n_segments
frac_hi = (i + 1) / n_segments
color = cmap((frac_lo + frac_hi) / 2)
y_bottom = cb_bottom + i * seg_height_m
rect = Rectangle(
(x0_data, y_bottom), cb_width_m, seg_height_m,
facecolor=color, edgecolor="black", linewidth=0.5,
clip_on=False, zorder=10,
)
ax.add_patch(rect)
if ticks is not None and ticklabels is not None:
for tick_val, tick_lbl in zip(ticks, ticklabels):
frac = (tick_val - vmin) / (vmax - vmin) if vmax > vmin else 0
frac = max(0, min(1, frac))
y_pos = cb_bottom + frac * cb_height_m
ax.plot(
[x0_data + cb_width_m, x0_data + cb_width_m + cb_width_m * 0.3],
[y_pos, y_pos],
color="black", linewidth=0.5, clip_on=False, zorder=10,
)
ax.text(
x0_data + cb_width_m + cb_width_m * 0.4, y_pos,
tick_lbl, fontsize=6, ha="left", va="center",
color="black", zorder=10,
)
if label:
ax.text(
x0_data + cb_width_m / 2, cb_bottom + cb_height_m + ax_height * 0.01,
label, fontsize=7, ha="center", va="bottom",
color="black", zorder=10,
)
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