diff --git a/server/map/__pycache__/get_relation.cpython-311.pyc b/server/map/__pycache__/get_relation.cpython-311.pyc
index 812af27f4b3e7b4696370419efaf670e47b9b2ff..76c8ff54db3931e76b092b850b48ecad05d4aa01 100644
Binary files a/server/map/__pycache__/get_relation.cpython-311.pyc and b/server/map/__pycache__/get_relation.cpython-311.pyc differ
diff --git a/server/map/get_relation.py b/server/map/get_relation.py
index b17ab008349f74516ffb79ca63635334ce33f5d9..15d0590ec75cb8f1268d4316be59c42b1d1a8a88 100644
--- a/server/map/get_relation.py
+++ b/server/map/get_relation.py
@@ -13,7 +13,7 @@ def get_relation(self, body_of_water: str):
# Filter only polygons, exclude points and other feature types to reduce response size
polygon_data = geo_data[geo_data['geometry'].geom_type == 'Polygon']
- if not polygon_data:
+ if polygon_data.empty:
raise ValueError("Failed to extract polygon data from file")
# Extract coordinates from polygons and create polygon objects
@@ -26,22 +26,30 @@ def get_relation(self, body_of_water: str):
# Divide all polygons into sections
for polygon in polygons:
- # Initialise grid
- grid_lines = create_grid(polygon, cell_size=0.1)
- hrz_lines = grid_lines[0] # Horizontal lines
- vrt_lines = grid_lines[1] # Vertical lines
+ # Divide the length and with of polygon into a grid
+ grid_lines = create_grid_coords(polygon, cell_size=0.1)
+
+ hrz_lines = grid_lines[0] # Horizontal coordinates
+ vrt_lines = grid_lines[1] # Vertical coordinates
# Cut polygon into horizontal sections
for hrz_line in hrz_lines:
- # Splits shape into upper and lower section by hrz_line
- cut_poly_1 = cut_polygon_in_two(polygon, hrz_line)
+ # Split shape into upper and lower section as hrz_line as divider
+ cut_poly_1 = cut_polygon_in_two(polygon, hrz_line, True)
polygon_part = cut_poly_1[0] # Save upper horizontal section
+ if not polygon_part or not cut_poly_1[0]:
+ continue
+
# Cut each horizontal section into vertical sections
for vrt_line in vrt_lines:
- cut_poly_2 = cut_polygon_in_two(polygon_part, vrt_line)
+ cut_poly_2 = cut_polygon_in_two(polygon_part, vrt_line, False)
+
+ if not cut_poly_2[0]:
+ continue
+
divided_map.extend(cut_poly_2[0]) # Append part to final list of shapes
# Set polygon_part to the remaining, un-split, horizontal section for next iteration
@@ -70,66 +78,50 @@ def get_relation(self, body_of_water: str):
self.wfile.write(tiles_json.encode('utf-8'))
-def cut_polygon_in_two(polygon, line):
- # Check for invalid parameters
- if not isinstance(polygon, Polygon) or not isinstance(line, LineString):
- print("Inputs must be Shapely Polygon and LineString obects")
-
+# Takes a polygon and divides its coordinates into two shapes, where divisor is a
+# coordinate that defines the point of division
+def cut_polygon_in_two(polygon: Polygon, divisor: float, horizontal: bool):
# Extract polygon exterior coordinates
exterior_coords = list(polygon.exterior.coords)
- # Initialize lists to store points for the two shapes
- shape_1 = []
- shape_2 = []
+ # Initialize lists to store coordinates of new shapes after split
+ split_shape = []
+ remaining_shape = []
- # Split points into separate shapes based on their location relative to the line
+ # Loop through points and check which side of the division line they are
for point in exterior_coords:
point = Point(point) # Convert coordinates to Shapely Point object
- if line.distance(point) < 1e-10: # Floating point error tolerance
- if line.contains(point): # Determine if point belongs to shape 1 or shape 2
- shape_1.append(point)
+ if horizontal: # Horizontal split
+ if point.y < divisor:
+ split_shape.append(point)
else:
- shape_2.append(point)
-
- # Check if shapes are empty
- if not shape_1 or not shape_2:
- raise ValueError("One or both shapes are empty after cutting")
-
- # Create Polygon objects from the lists of points
- poly_1 = Polygon(shape_1)
- poly_2 = Polygon(shape_2)
+ remaining_shape.append(point)
+ else: # Vertical split
+ if point.x < divisor:
+ split_shape.append(point)
+ else:
+ remaining_shape.append(point)
- return poly_1, poly_2
+ # Check if polygons have enough coordinates
+ if len(split_shape) < 3 or len(remaining_shape) < 3:
+ print("Not enough coordinates to create valid polygons")
+ return None, None
+ # Append the first coordinate of the shapes to create closed loop
+ split_shape.append(split_shape[0]) # NB: may not be necessary?
+ remaining_shape.append(remaining_shape[0])
-# From https://stackoverflow.com/questions/39338550/cut-a-polygon-with-two-lines-in-shapely
-# Splits a polygon into two parts based on a dividing line
-def cut_polygon_by_line(polygon, line):
- if polygon.geom_type == 'Polygon':
- polygon = [polygon]
- merged = linemerge([poly.boundary for poly in polygon] + [line])
- borders = unary_union(merged)
- polygons = polygonize(borders)
- return list(polygons)
+ return Polygon(split_shape), Polygon(remaining_shape) # Return split polygons as Shapely Polygon objects
-# Create a grid of lines spaced by a cell size
-def create_grid(polygon, cell_size):
+# Generate grid of equally spaced x and y coordinates where the grid size is determined by cell_size
+def create_grid_coords(polygon: Polygon, cell_size: float):
min_x, min_y, max_x, max_y = polygon.bounds
x_coords = np.arange(min_x, max_x, cell_size)
y_coords = np.arange(min_y, max_y, cell_size)
- horizontal_lines = []
- vertical_lines = []
-
- # Vertical lines from top to bottom
- for x in x_coords:
- vertical_lines.append(LineString([(x, min_y), (x, max_y)]))
- # Horizontal lines from top to bottom
- for y in y_coords:
- horizontal_lines.append(LineString([(min_x, y), (max_x, y)]))
+ if len(x_coords) == 0 or len(y_coords) == 0:
+ raise ValueError("No grid points generated")
- if not horizontal_lines or not vertical_lines:
- raise ValueError("List of horizontal or vertical lines is empty")
+ return x_coords, y_coords
- return horizontal_lines, vertical_lines