""" ============== Filled polygon ============== `~.Axes.fill()` draws a filled polygon based on lists of point coordinates *x*, *y*. This example uses the `Koch snowflake`_ as an example polygon. .. _Koch snowflake: https://en.wikipedia.org/wiki/Koch_snowflake """ import matplotlib.pyplot as plt import numpy as np def koch_snowflake(order, scale=10): """ Return two lists x, y of point coordinates of the Koch snowflake. Parameters ---------- order : int The recursion depth. scale : float The extent of the snowflake (edge length of the base triangle). """ def _koch_snowflake_complex(order): if order == 0: # initial triangle angles = np.array([0, 120, 240]) + 90 return scale / np.sqrt(3) * np.exp(np.deg2rad(angles) * 1j) else: ZR = 0.5 - 0.5j * np.sqrt(3) / 3 p1 = _koch_snowflake_complex(order - 1) # start points p2 = np.roll(p1, shift=-1) # end points dp = p2 - p1 # connection vectors new_points = np.empty(len(p1) * 4, dtype=np.complex128) new_points[::4] = p1 new_points[1::4] = p1 + dp / 3 new_points[2::4] = p1 + dp * ZR new_points[3::4] = p1 + dp / 3 * 2 return new_points points = _koch_snowflake_complex(order) x, y = points.real, points.imag return x, y # %% # Basic usage: x, y = koch_snowflake(order=5) plt.figure(figsize=(8, 8)) plt.axis('equal') plt.fill(x, y) plt.show() # %% # Use keyword arguments *facecolor* and *edgecolor* to modify the colors # of the polygon. Since the *linewidth* of the edge is 0 in the default # Matplotlib style, we have to set it as well for the edge to become visible. x, y = koch_snowflake(order=2) fig, (ax1, ax2, ax3) = plt.subplots(1, 3, figsize=(9, 3), subplot_kw={'aspect': 'equal'}) ax1.fill(x, y) ax2.fill(x, y, facecolor='lightsalmon', edgecolor='orangered', linewidth=3) ax3.fill(x, y, facecolor='none', edgecolor='purple', linewidth=3) plt.show() # %% # # .. admonition:: References # # The use of the following functions, methods, classes and modules is shown # in this example: # # - `matplotlib.axes.Axes.fill` / `matplotlib.pyplot.fill` # - `matplotlib.axes.Axes.axis` / `matplotlib.pyplot.axis` # # .. tags:: # # styling: shape # level: beginner # purpose: showcase