Merge 06f0dc3 into d7db0ef

contextily/tile.py

@@ -93,7 +93,7 @@ def bounds2raster(w, s, e, n, path, zoom='auto',
 
 
 def bounds2img(w, s, e, n, zoom='auto',
-               url=sources.ST_TERRAIN, ll=False,
+               url=sources.ST_TERRAIN, path=None, ll=False,
                wait=0, max_retries=2):
     '''
     Take bounding box and zoom and return an image with all the tiles
@@ -121,6 +121,11 @@ def bounds2img(w, s, e, n, zoom='auto',
     ll      : Boolean
               [Optional. Default: False] If True, `w`, `s`, `e`, `n` are
               assumed to be lon/lat as opposed to Spherical Mercator.
+    path    : str
+              [Optional. Default: None] If a path is given the tiles will be
+              downloaded to this location. If the tile can be found in the
+              given path the local tile will be used instead of the server
+              tile. This is faster and will reduce server usage.
     wait    : int
               [Optional. Default: 0]
               if the tile API is rate-limited, the number of seconds to wait
@@ -147,9 +152,13 @@ def bounds2img(w, s, e, n, zoom='auto',
     arrays = []
     for t in mt.tiles(w, s, e, n, [zoom]):
         x, y, z = t.x, t.y, t.z
-        tile_url = url.replace('tileX', str(x)).replace('tileY', str(y)).replace('tileZ', str(z))
+        tile_url = url.replace(
+            'tileX', str(x)).replace('tileY', str(y)).replace('tileZ', str(z))
         # ---
-        image = _fetch_tile(tile_url, wait, max_retries)
+        if path is not None:
+            image = _fetch_tile_with_cache(tile_url, wait, max_retries, path)
+        else:
+            image = _fetch_tile(tile_url, wait, max_retries)
         # ---
         tiles.append(t)
         arrays.append(image)
@@ -162,6 +171,33 @@ def bounds2img(w, s, e, n, zoom='auto',
     return merged, extent
 
 
+def _fetch_tile_with_cache(tile_url, wait, max_retries, path):
+    """
+    Fetch local tile or try to download file if local file is not present.
+
+    Sometimes OSM servers deny requests via Python scripts but allows direct
+    downloads. In that case one can try to download the file manually using the
+    given url and filename.
+    """
+
+    fn = tile_url.replace('https://', '').replace('http://', '')
+    fn = fn.replace('/', '_')
+    image_path = os.path.join(path, fn)
+
+    if not os.path.isfile(image_path):
+        request = _retryer(tile_url, wait, max_retries)
+        if request.status_code == 200:
+            with open(image_path, 'wb') as f:
+                for chunk in request:
+                    f.write(chunk)
+        else:
+            request.raise_for_status()
+
+    image = Image.open(image_path).convert('RGB')
+    image = np.asarray(image)
+    return image
+
+
 def _fetch_tile(tile_url, wait, max_retries):
     request = _retryer(tile_url, wait, max_retries)
     with io.BytesIO(request.content) as image_stream: