barycentre.py

#! /usr/bin/env python3

# http://ifcuriousthenlearn.com/blog/2015/06/18/center-of-mass/
import numpy as np
import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D

#set plot sizes
plt.rcParams['figure.figsize'] = (10, 2)  # (width, height)
plt.rcParams['font.size'] = 20
plt.rcParams['legend.fontsize'] = 16


x = np.array([ 1,  7,  7, 11,    2.5])
y = np.array([10, 19, 10, 14.5, -0.2])
m = np.array([20, 10, 10,  7,    5  ])

cgx = np.sum(x * m) / np.sum(m)
print('The center of mass in x is %f' % cgx)

cgy = np.sum(y * m) / np.sum(m)
print('The center of mass in y is %f' % cgy)

plt.rcParams['figure.figsize'] = (6, 10)  # (width, height)
plt.scatter(x,y,s=m);
plt.scatter(cgx, cgy, color='k', marker='+', s=1e4);
plt.title('Center of Gravity')

plt.show()