import matplotlib.pyplot as plt
import numpy as np

file = open('tesffile.txt', 'w')
dt = 0.01
t = np.arange(0, 10, dt)
nse = np.random.randn(len(t))
r = np.exp(-t/0.05)

cnse = np.convolve(nse, r)*dt
cnse = cnse[:len(t)]
s = 0.1*np.sin(2*np.pi*t) + cnse

plt.psd(s, 64, 1/dt)
plt.title('Plot')
plt.xlabel('X')
plt.ylabel('Y')
plt.grid(True)

ax = plt.gca()
line = ax.lines[0]

ydata = line.get_ydata()
xdata = line.get_xdata()

ymax = -999999
imax = -1
i = 0
while i < len(ydata):
    if ydata[i] > ymax:
        ymax = ydata[i]
        imax = i
    print(xdata[i], ydata[i])
    s = str(xdata[i])
    s += ' '
    s += str(ydata[i])
    s += '\r\n'
    file.write(s)
    i += 1

print
print xdata[imax], ymax
file.close()
plt.show()