Python animated radar chart

Question

I'm trying to create a radar chart using Python / Matplotlib where measured data can be "played back" using matplotlib's built in animation module. I want the data points to move along their respective axes as the data set is traversed. I have problems reading the data and updating the chart, nor am I able to find an example of this.

I have attached a piece of code that should give you an idea of what I am trying to achieve:

import matplotlib.pyplot as plt
import matplotlib.animation as animation
from math import pi


class SubplotAnimation(animation.TimedAnimation):
    def __init__(self, data):

        self.data = data
        fig = plt.figure()
        ax = fig.add_subplot(111, projection='polar')

        # Figure definition
        cat = ['A', 'B', 'C', 'D', 'E']
        values = [10, 10, 10, 10, 10]

        N = len(cat)

        x_as = [n / float(N) * 2 * pi for n in range(N)]

        # Because our chart will be circular we need to append a copy of
        # the first value of each list at the end of each list with data
        values += values[:1]
        x_as += x_as[:1]

        plt.rc('axes', linewidth=0.5, edgecolor='#888888')  # Set color of axes

        # Create polar plot
        ax = plt.subplot(111, projection='polar')

        # Set clockwise rotation. That is:
        ax.set_theta_offset(pi / 2)
        ax.set_theta_direction(-1)

        # Set position of y-labels
        ax.set_rlabel_position(0)

        # Set color and linestyle of grid
        ax.xaxis.grid(True, color="#888888", linestyle='solid', linewidth=0.5)
        ax.yaxis.grid(True, color="#888888", linestyle='solid', linewidth=0.5)

        # Set number of radial axes and remove labels
        plt.xticks(x_as[:-1], [])

        # Set yticks
        plt.yticks([20, 40, 60, 80, 100], ["20", "40", "60", "80", "100"])

        # Set axes limits
        plt.ylim(0, 100)

        # Draw ytick labels to make sure they fit properly
        for i in range(N):
            angle_rad = i / float(N) * 2 * pi

            if angle_rad == 0:
                ha, distance_ax = "center", 10
            elif 0 < angle_rad < pi:
                ha, distance_ax = "left", 1
            elif angle_rad == pi:
                ha, distance_ax = "center", 1
            else:
                ha, distance_ax = "right", 1

        ax.text(angle_rad, 100 + distance_ax, cat[i], size=10,
                horizontalalignment=ha, verticalalignment="center")

        animation.TimedAnimation.__init__(self, fig, interval=25, blit=True)

        def new_frame_seq(self):
            return iter(range(len(self.data)))

        def _draw_frame(self, framedata):
            ax.plot(ax, framedata)

testdata = [[10, 20, 30, 40, 50],
            [10, 20, 30, 40, 50],
            [40, 50, 60, 70, 80],
            [40, 50, 60, 70, 80],
            [50, 60, 70, 80, 90]]

ani = SubplotAnimation(testdata)
plt.show()

Any tips on how to make this work will be greatly appreciated!

Answer 1

It's not clear what the aim of subclassing TimedAnimation would be. It makes things much too complicated.

Here is a simple example of an animated radar plot using FuncAnimation.

import matplotlib.pyplot as plt
import matplotlib.animation as animation
import numpy as np

fig = plt.figure(figsize=(4,4))
ax = fig.add_subplot(111, projection='polar')
ax.set_ylim(0,100)

data = np.random.rand(50)*6+2
theta = np.linspace(0,2.*np.pi, num=50)
l,  = ax.plot([],[])

def update(i):
    global data
    data += (np.random.rand(50)+np.cos(i*2.*np.pi/50.))*2 
    data[-1] = data[0]
    l.set_data(theta, data )
    return l, 

ani = animation.FuncAnimation(fig, update, frames=50, interval=200, blit=True)
plt.show()