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import os |
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import hashlib |
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import tempfile |
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import contextily as ctx |
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from mpl_toolkits.basemap import Basemap |
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import cartopy.crs as ccrs |
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import cartopy.feature as cfeature |
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from PIL import Image |
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import matplotlib.pyplot as plt |
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def get_cache_dir(app_name): |
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if os.name == 'nt': |
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return os.path.join(os.getenv('LOCALAPPDATA', tempfile.gettempdir()), f"{app_name}_cache") |
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elif os.name == 'posix': |
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home_dir = os.path.expanduser("~") |
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if os.path.isdir(home_dir) and os.access(home_dir, os.W_OK): |
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return os.path.join(home_dir, f".{app_name}_cache") |
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else: |
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return os.path.join(tempfile.gettempdir(), f"{app_name}_cache") |
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else: |
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return os.path.join(tempfile.gettempdir(), f"{app_name}_cache") |
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CTX_TILE_CACHE_DIR = get_cache_dir("contextily") |
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BASEMAP_TILE_CACHE_DIR = get_cache_dir("basemap") |
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os.environ["XDG_CACHE_HOME"] = CTX_TILE_CACHE_DIR |
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os.makedirs(CTX_TILE_CACHE_DIR, exist_ok=True) |
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os.makedirs(BASEMAP_TILE_CACHE_DIR, exist_ok=True) |
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def draw_etopo_basemap(ax, mode="basemap", zoom=11): |
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""" |
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Draws a high-resolution basemap background on the provided Cartopy GeoAxes. |
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Parameters |
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---------- |
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ax : matplotlib.axes._subplots.AxesSubplot |
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The matplotlib Axes object (with Cartopy projection) to draw the map background on. |
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mode : str, optional |
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The basemap mode to use: |
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- "stock": Default stock image from Cartopy. |
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- "contextily": Web tile background (CartoDB Voyager), with caching. |
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- "basemap": High-resolution shaded relief using Basemap, with caching. |
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Default is "basemap". |
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zoom : int, optional |
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Tile zoom level (only for "contextily"). Higher = more detail. Default is 7. |
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Notes |
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----- |
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- Uses high resolution for Basemap (resolution='h') and saves figure at 300 DPI. |
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- Cached images are reused using extent-based hashing to avoid re-rendering. |
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- Basemap is deprecated; Cartopy with web tiles is recommended for new projects. |
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""" |
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try: |
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if mode == "stock": |
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ax.stock_img() |
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elif mode == "contextily": |
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extent = ax.get_extent(crs=ccrs.PlateCarree()) |
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ax.set_extent(extent, crs=ccrs.PlateCarree()) |
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ctx.add_basemap( |
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ax, |
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crs=ccrs.PlateCarree(), |
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source=ctx.providers.CartoDB.Voyager, |
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zoom=zoom |
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) |
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elif mode == "basemap": |
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extent = ax.get_extent(crs=ccrs.PlateCarree()) |
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extent_str = f"{extent[0]:.4f}_{extent[1]:.4f}_{extent[2]:.4f}_{extent[3]:.4f}" |
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cache_key = hashlib.md5(extent_str.encode()).hexdigest() |
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cache_file = os.path.join(BASEMAP_TILE_CACHE_DIR, f"{cache_key}_highres.png") |
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if os.path.exists(cache_file): |
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img = Image.open(cache_file) |
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ax.imshow(img, extent=extent, transform=ccrs.PlateCarree()) |
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else: |
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temp_fig, temp_ax = plt.subplots(figsize=(12, 9), |
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subplot_kw={'projection': ccrs.PlateCarree()}) |
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temp_ax.set_extent(extent, crs=ccrs.PlateCarree()) |
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m = Basemap(projection='cyl', |
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llcrnrlon=extent[0], urcrnrlon=extent[1], |
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llcrnrlat=extent[2], urcrnrlat=extent[3], |
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resolution='f', ax=temp_ax) |
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m.shadedrelief() |
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temp_fig.savefig(cache_file, dpi=300, bbox_inches='tight', pad_inches=0) |
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plt.close(temp_fig) |
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img = Image.open(cache_file) |
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ax.imshow(img, extent=extent, transform=ccrs.PlateCarree()) |
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else: |
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raise ValueError(f"Unsupported basemap mode: {mode}") |
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except Exception as e: |
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print(f"[Relief Error - {mode} mode]:", e) |
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ax.add_feature(cfeature.LAND) |
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ax.add_feature(cfeature.OCEAN) |
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