Wednesday, April 27, 2016

Plot histogram on a clock

Today I want to plot a histogram on a 24 hour clock (the data is aggregated from real life data that bined on each hour of the day). Here's the code, and you can download the code from Qingkai's Github.
In [1]:
import numpy as np
import matplotlib.pyplot as plt
import seaborn as sns
sns.set_context('poster')
sns.set_style('white')
%pylab inline

Populating the interactive namespace from numpy and matplotlib


(1) First generate random data from 0 - 23¶

In [2]:
arr = np.random.randint(0, 24, size = 500)


(2) Plot on the clock¶

In [3]:
N = 23
bottom = 2

# create theta for 24 hours
theta = np.linspace(0.0, 2 * np.pi, N, endpoint=False)

# make the histogram that bined on 24 hour
radii, tick = np.histogram(arr, bins = 23)

# width of each bin on the plot
width = (2*np.pi) / N

# make a polar plot
plt.figure(figsize = (12, 8))
ax = plt.subplot(111, polar=True)
bars = ax.bar(theta, radii, width=width, bottom=bottom)

# set the lable go clockwise and start from the top
ax.set_theta_zero_location("N")
# clockwise
ax.set_theta_direction(-1)

# set the label
ticks = ['0:00', '3:00', '6:00', '9:00', '12:00', '15:00', '18:00', '21:00']
ax.set_xticklabels(ticks)

plt.show()

In [ ]: