Add function to plot polygons (#347)

The new function now plots the polygons correctly, meaning no longer overlapping of the fill color and the lines for narrow line widths. This will also remove the error of gaps in the boundary at the closing point of the polygons.

Author: schroedtert

pedpy/plotting/plotting.py

@@ -9,6 +9,7 @@
 import numpy as np
 import pandas as pd
 import shapely
+from matplotlib.patches import Polygon
 from mpl_toolkits.axes_grid1 import make_axes_locatable
 from numpy.typing import NDArray
 
@@ -39,6 +40,87 @@
 PEDPY_RED = (233 / 255, 117 / 255, 134 / 255)
 
 
+def _plot_polygon(
+    *,
+    axes: matplotlib.axes.Axes,
+    polygon: shapely.Polygon,
+    polygon_color: Any,
+    polygon_alpha: float = 1,
+    line_color: Any = PEDPY_GREY,
+    line_width: float = 1,
+    hole_color: Any = "lightgrey",
+    hole_alpha: float = 1,
+) -> matplotlib.axes.Axes:
+    """Plot the shapely polygon (including holes).
+
+    Args:
+        polygon (shapely.Polygon): polygon to plot
+        axes (matplotlib.axes.Axes): Axes to plot on, if None new will be created
+        polygon_color (Any): background color of the polygon
+        polygon_alpha (float): alpha of the background for the polygon
+        line_color (Any): color of the borders
+        line_width (float): line width of the borders
+        hole_color (Any): background color of holes
+        hole_alpha (float): alpha of background color for holes
+
+    Returns:
+        matplotlib.axes.Axes instance where the polygon is plotted
+
+    """
+    # Plot the boundary of the polygon/holes separately to get the same color
+    # as the outside as alpha modifies all colors
+
+    # Plot the exterior of the polygon
+    exterior_coords = list(polygon.exterior.coords)
+    exterior_polygon_border = Polygon(
+        exterior_coords,
+        edgecolor=line_color,
+        facecolor="none",
+        linewidth=line_width,
+        closed=True,
+        zorder=1000,
+    )
+    axes.add_patch(exterior_polygon_border)
+
+    exterior_polygon_fill = Polygon(
+        exterior_coords,
+        edgecolor="none",
+        facecolor=polygon_color,
+        linewidth=line_width,
+        alpha=polygon_alpha,
+        closed=True,
+        zorder=1000,
+    )
+    axes.add_patch(exterior_polygon_fill)
+
+    # Plot the interiors (holes) of the polygon
+    for interior in polygon.interiors:
+        interior_coords = list(interior.coords)
+        interior_polygon_border = Polygon(
+            interior_coords,
+            edgecolor=line_color,
+            facecolor="none",
+            linewidth=line_width,
+            alpha=1,
+            closed=True,
+            zorder=1000,
+        )
+        axes.add_patch(interior_polygon_border)
+
+        interior_polygon_fill = Polygon(
+            interior_coords,
+            edgecolor="none",
+            facecolor=hole_color,
+            linewidth=line_width,
+            alpha=hole_alpha,
+            closed=True,
+            zorder=1000,
+        )
+        axes.add_patch(interior_polygon_fill)
+
+    return axes
+
+
 def _plot_series(  # pylint: disable=too-many-arguments
     axes: matplotlib.axes.Axes,
     title: str,
@@ -362,8 +444,13 @@ def plot_neighborhood(
             color = neighbor_color
             alpha = 0.5
 
-        axes.plot(*poly.exterior.xy, alpha=1, color=color)
-        axes.fill(*poly.exterior.xy, alpha=alpha, color=color)
+        _plot_polygon(
+            axes=axes,
+            polygon=poly,
+            line_color=color,
+            polygon_color=color,
+            polygon_alpha=alpha,
+        )
         axes.set_aspect("equal")
 
     return axes
@@ -521,21 +608,21 @@ def plot_walkable_area(
     hole_color = kwargs.pop("hole_color", "lightgrey")
     hole_alpha = kwargs.pop("hole_alpha", 1.0)
 
-    axes.plot(
-        *walkable_area.polygon.exterior.xy,
-        color=line_color,
-        linewidth=line_width,
+    axes = _plot_polygon(
+        polygon=walkable_area.polygon,
+        polygon_color="none",
+        line_color=line_color,
+        line_width=line_width,
+        hole_color=hole_color,
+        hole_alpha=hole_alpha,
+        axes=axes,
     )
 
-    for hole in walkable_area.polygon.interiors:
-        axes.plot(*hole.xy, color=line_color, linewidth=line_width)
-        # Paint all holes first white, then with the desired color
-        axes.fill(*hole.xy, color="w", alpha=1)
-        axes.fill(*hole.xy, color=hole_color, alpha=hole_alpha)
-
     axes.set_xlabel(r"x/m")
     axes.set_ylabel(r"y/m")
 
+    axes.autoscale_view()
+
     return axes
 
 
@@ -660,25 +747,23 @@ def plot_measurement_setup(
     if axes is None:
         axes = plt.gca()
 
+    if measurement_areas is not None:
+        for measurement_area in measurement_areas:
+            _plot_polygon(
+                axes=axes,
+                polygon=measurement_area.polygon,
+                line_color=ma_line_color,
+                line_width=ma_line_width,
+                polygon_alpha=ma_alpha,
+                polygon_color=ma_color,
+            )
+
     if walkable_area is not None:
         plot_walkable_area(walkable_area=walkable_area, axes=axes, **kwargs)
 
     if traj is not None:
         plot_trajectories(traj=traj, walkable_area=None, axes=axes, **kwargs)
 
-    if measurement_areas is not None:
-        for measurement_area in measurement_areas:
-            axes.plot(
-                *measurement_area.polygon.exterior.xy,
-                color=ma_line_color,
-                linewidth=ma_line_width,
-            )
-            axes.fill(
-                *measurement_area.polygon.exterior.xy,
-                color=ma_color,
-                alpha=ma_alpha,
-            )
-
     if measurement_lines is not None:
         for measurement_line in measurement_lines:
             axes.plot(*measurement_line.xy, color=ml_color, linewidth=ml_width)
@@ -810,18 +895,23 @@ def inverse(values):
         else:
             color = np.array([1, 1, 1])
 
-        axes.plot(*poly.exterior.xy, alpha=1, color=voronoi_border_color)
-        axes.fill(
-            *poly.exterior.xy, facecolor=color, alpha=voronoi_outside_ma_alpha
+        _plot_polygon(
+            axes=axes,
+            polygon=poly,
+            line_color=voronoi_border_color,
+            polygon_color=color,
+            polygon_alpha=voronoi_outside_ma_alpha,
         )
 
         if INTERSECTION_COL in data.columns:
             if not shapely.is_empty(row[INTERSECTION_COL]):
                 intersection_poly = row[INTERSECTION_COL]
-                axes.fill(
-                    *intersection_poly.exterior.xy,
-                    facecolor=color,
-                    alpha=voronoi_inside_ma_alpha,
+                _plot_polygon(
+                    axes=axes,
+                    polygon=intersection_poly,
+                    line_color="none",
+                    polygon_color=color,
+                    polygon_alpha=voronoi_inside_ma_alpha,
                 )
 
         if traj_data: