.. _animation-rain: animation example code: rain.py =============================== [`source code `_] :: """ Rain simulation Simulates rain drops on a surface by animating the scale and opacity of 50 scatter points. Author: Nicolas P. Rougier """ import numpy as np import matplotlib.pyplot as plt from matplotlib.animation import FuncAnimation # Create new Figure and an Axes which fills it. fig = plt.figure(figsize=(7,7)) ax = fig.add_axes([0, 0, 1, 1], frameon=False) ax.set_xlim(0,1), ax.set_xticks([]) ax.set_ylim(0,1), ax.set_yticks([]) # Create rain data n_drops = 50 rain_drops = np.zeros(n_drops, dtype=[('position', float, 2), ('size', float, 1), ('growth', float, 1), ('color', float, 4)]) # Initialize the raindrops in random positions and with # random growth rates. rain_drops['position'] = np.random.uniform(0, 1, (n_drops, 2)) rain_drops['growth'] = np.random.uniform(50, 200, n_drops) # Construct the scatter which we will update during animation # as the raindrops develop. scat = ax.scatter(rain_drops['position'][:,0], rain_drops['position'][:,1], s=rain_drops['size'], lw=0.5, edgecolors=rain_drops['color'], facecolors='none') def update(frame_number): # Get an index which we can use to re-spawn the oldest raindrop. current_index = frame_number % n_drops # Make all colors more transparent as time progresses. rain_drops['color'][:, 3] -= 1.0/len(rain_drops) rain_drops['color'][:,3] = np.clip(rain_drops['color'][:,3], 0, 1) # Make all circles bigger. rain_drops['size'] += rain_drops['growth'] # Pick a new position for oldest rain drop, resetting its size, # color and growth factor. rain_drops['position'][current_index] = np.random.uniform(0, 1, 2) rain_drops['size'][current_index] = 5 rain_drops['color'][current_index] = (0, 0, 0, 1) rain_drops['growth'][current_index] = np.random.uniform(50, 200) # Update the scatter collection, with the new colors, sizes and positions. scat.set_edgecolors(rain_drops['color']) scat.set_sizes(rain_drops['size']) scat.set_offsets(rain_drops['position']) # Construct the animation, using the update function as the animation # director. animation = FuncAnimation(fig, update, interval=10) plt.show() Keywords: python, matplotlib, pylab, example, codex (see :ref:`how-to-search-examples`)