# Plotting columns of data from a file

import pandas as pd
import numpy as np
import matplotlib.pyplot as plt

df = pd.read_csv('spring_midpoint.dat',sep='\s+',names=['t','y','vy','E'])

plt.plot(df.t,df.y,label='y(t)')
plt.plot(df.t,df.vy,label='v(t)')
plt.plot(df.t,df.E,label='E(t)')

# label axes
plt.xlabel('t (s)')
plt.ylabel('y (m), $v_y$ (m/s) or E (J)')

# axes scales
#plt.xlim(0,10)
#plt.ylim(-5,5)
plt.legend()

# save the plot as an image
plt.savefig('midpoint.pdf')
#plt.savefig('midpoint.eps',format='eps')

#plt.show()