8000 Added example on how to make packed bubble charts (#18223) · matplotlib/matplotlib@efa8bb0 · GitHub
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Added example on how to make packed bubble charts (#18223)
* Added example on how to make packed bubble charts * fixed style errors * Apply suggestions from code review Co-authored-by: Tim Hoffmann <2836374+timhoffm@users.noreply.github.com> * Apply suggestions from code review Co-authored-by: Jody Klymak <jklymak@gmail.com> * applied rewiews * fixed typo * readded title * style fix * Apply suggestions from code review * removed blank line * nicer array casting * Apply suggestions from code review * fixed variable names in docstring Co-authored-by: Tim Hoffmann <2836374+timhoffm@users.noreply.github.com> Co-authored-by: Jody Klymak <jklymak@gmail.com>
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‎examples/misc/packed_bubbles.py

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"""
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===================
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Packed-bubble chart
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===================
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Create a packed-bubble chart to represent scalar data.
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The presented algorithm tries to move all bubbles as close to the center of
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mass as possible while avoiding some collisions by moving around colliding
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objects. In this example we plot the market share of different desktop
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browsers.
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(source: https://gs.statcounter.com/browser-market-share/desktop/worldwidev)
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"""
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import numpy as np
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import matplotlib.pyplot as plt
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browser_market_share = {
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'browsers': ['firefox', 'chrome', 'safari', 'edge', 'ie', 'opera'],
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'market_share': [8.61, 69.55, 8.36, 4.12, 2.76, 2.43],
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'color': ['#5A69AF', '#579E65', '#F9C784', '#FC944A', '#F24C00', '#00B825']
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}
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class BubbleChart:
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def __init__(self, area, bubble_spacing=0):
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"""
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Setup for bubble collapse.
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Parameters
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----------
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area : array-like
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Area of the bubbles.
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bubble_spacing : float, default: 0
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Minimal spacing between bubbles after collapsing.
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Notes
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-----
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If "area" is sorted, the results might look weird.
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"""
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area = np.asarray(area)
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r = np.sqrt(area / np.pi)
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self.bubble_spacing = bubble_spacing
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self.bubbles = np.ones((len(area), 4))
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self.bubbles[:, 2] = r
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self.bubbles[:, 3] = area
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self.maxstep = 2 * self.bubbles[:, 2].max() + self.bubble_spacing
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self.step_dist = self.maxstep / 2
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# calculate initial grid layout for bubbles
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length = np.ceil(np.sqrt(len(self.bubbles)))
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grid = np.arange(length) * self.maxstep
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gx, gy = np.meshgrid(grid, grid)
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self.bubbles[:, 0] = gx.flatten()[:len(self.bubbles)]
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self.bubbles[:, 1] = gy.flatten()[:len(self.bubbles)]
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self.com = self.center_of_mass()
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def center_of_mass(self):
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return np.average(
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self.bubbles[:, :2], axis=0, weights=self.bubbles[:, 3]
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)
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def center_distance(self, bubble, bubbles):
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return np.hypot(bubble[0] - bubbles[:, 0],
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bubble[1] - bubbles[:, 1])
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def outline_distance(self, bubble, bubbles):
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center_distance = self.center_distance(bubble, bubbles)
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return center_distance - bubble[2] - \
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bubbles[:, 2] - self.bubble_spacing
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def check_collisions(self, bubble, bubbles):
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distance = self.outline_distance(bubble, bubbles)
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return len(distance[distance < 0])
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def collides_with(self, bubble, bubbles):
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distance = self.outline_distance(bubble, bubbles)
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idx_min = np.argmin(distance)
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return idx_min if type(idx_min) == np.ndarray else [idx_min]
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def collapse(self, n_iterations=50):
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"""
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Move bubbles to the center of mass.
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Parameters
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----------
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n_iterations : int, default: 50
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Number of moves to perform.
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"""
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for _i in range(n_iterations):
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moves = 0
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for i in range(len(self.bubbles)):
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rest_bub = np.delete(self.bubbles, i, 0)
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# try to move directly towards the center of mass
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# direction vector from bubble to the center of mass
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dir_vec = self.com - self.bubbles[i, :2]
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# shorten direction vector to have length of 1
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dir_vec = dir_vec / np.sqrt(dir_vec.dot(dir_vec))
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# calculate new bubble position
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new_point = self.bubbles[i, :2] + dir_vec * self.step_dist
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new_bubble = np.append(new_point, self.bubbles[i, 2:4])
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# check whether new bubble collides with other bubbles
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if not self.check_collisions(new_bubble, rest_bub):
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self.bubbles[i, :] = new_bubble
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self.com = self.center_of_mass()
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moves += 1
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else:
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# try to move around a bubble that you collide with
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# find colliding bubble
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for colliding in self.collides_with(new_bubble, rest_bub):
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# calculate direction vector
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dir_vec = rest_bub[colliding, :2] - self.bubbles[i, :2]
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dir_vec = dir_vec / np.sqrt(dir_vec.dot(dir_vec))
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# calculate orthagonal vector
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orth = np.array([dir_vec[1], -dir_vec[0]])
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# test which direction to go
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new_point1 = (self.bubbles[i, :2] + orth *
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self.step_dist)
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new_point2 = (self.bubbles[i, :2] - orth *
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self.step_dist)
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dist1 = self.center_distance(
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self.com, np.array([new_point1]))
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dist2 = self.center_distance(
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self.com, np.array([new_point2]))
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new_point = new_point1 if dist1 < dist2 else new_point2
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new_bubble = np.append(new_point, self.bubbles[i, 2:4])
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if not self.check_collisions(new_bubble, rest_bub):
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self.bubbles[i, :] = new_bubble
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self.com = self.center_of_mass()
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if moves / len(self.bubbles) < 0.1:
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self.step_dist = self.step_dist / 2
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def plot(self, ax, labels, colors):
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"""
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Draw the bubble plot.
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Parameters
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----------
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ax : matplotlib.axes.Axes
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labels : list
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Labels of the bubbles.
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colors : list
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Colors of the bubbles.
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"""
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for i in range(len(self.bubbles)):
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circ = plt.Circle(
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self.bubbles[i, :2], self.bubbles[i, 2], color=colors[i])
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ax.add_patch(circ)
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ax.text(*self.bubbles[i, :2], labels[i],
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horizontalalignment='center', verticalalignment='center')
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bubble_chart = BubbleChart(area=browser_market_share['market_share'],
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bubble_spacing=0.1)
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bubble_chart.collapse()
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fig, ax = plt.subplots(subplot_kw=dict(aspect="equal"))
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bubble_chart.plot(
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ax, browser_market_share['browsers'], browser_market_share['color'])
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ax.axis("off")
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ax.relim()
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ax.autoscale_view()
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ax.set_title('Browser market share')
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plt.show()

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