making date plots with python matplotlib

#making date plots with python matplotlib
#is usefull when do yu have a date in the xaxis and a valur (int, float...) in the yaxis
#Author: Wagner Cipriano
#Ref1: https://stackoverflow.com/questions/33962255/valueerror-invalid-literal-for-float-17-08-2015
#Ref2: http://matplotlib.org/examples/pylab_examples/date_demo1.html
#Python version tested successfully: 2.7.12

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
from matplotlib.dates import DateFormatter
from random import randrange, random
from datetime import datetime

#generate date list
start_date = np.datetime64('2010-01-01').astype(datetime)

numdays = 10
dates = pd.date_range(start_date, periods=numdays)

#Generate data example
data1 = [(random()+idx)**1.2 for idx in range(len(dates))]
data2 = [(random()+idx)**1.5 for idx in range(len(dates))]

#plot
fig, ax = plt.subplots()
ax.plot_date(dates, data1, '-')
ax.plot_date(dates, data2, '-')

#set the label for x and y and title
plt.title('Matplot lib dates wc example')
plt.xlabel('Dates')
plt.ylabel('Random values example')

#date format
ax.fmt_xdata = DateFormatter('%Y%m%d')
#ax.fmt_ydata = data1
ax.grid(True)
fig.autofmt_xdate()

plt.show()