# coding: utf-8

# In[13]:


"""
=====
Decay
=====

This example showcases a sinusoidal decay animation.
"""

#import numpy as np
#import matplotlib as mpl
#import matplotlib.pyplot as plt
get_ipython().run_line_magic('pylab', 'inline')
import matplotlib.animation as animation
from IPython.display import HTML

def data_gen(t=0):
    cnt = 0
    while cnt < 1000:
        cnt += 1
        t += 0.1
        yield t, np.sin(2*np.pi*t) * np.exp(-t/10.)


def init():
    ax.set_ylim(-1.1, 1.1)
    ax.set_xlim(0, 10)
    del xdata[:]
    del ydata[:]
    line.set_data(xdata, ydata)
    return line,


plt.xkcd()
fig, ax = plt.subplots()
line, = ax.plot([], [], lw=2)
ax.grid()
xdata, ydata = [], []


def run(data):
    # update the data
    t, y = data
    xdata.append(t)
    ydata.append(y)
    xmin, xmax = ax.get_xlim()

    if t >= xmax:
        ax.set_xlim(xmin, 2*xmax)
        ax.figure.canvas.draw()
    line.set_data(xdata, ydata)

    return line,

ani = animation.FuncAnimation(fig, run, data_gen, blit=True, interval=25,
                              repeat=True, init_func=init)
HTML(ani.to_html5_video())