add line to plot matplotlib code example

Example 1: matplotlib line plot

from matplotlib import pyplot as plt

# Median Developer Salaries by Age
dev_x = [25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35]

dev_y = [38496, 42000, 46752, 49320, 53200,
         56000, 62316, 64928, 67317, 68748, 73752]

plt.plot(dev_x, dev_y)
plt.xlabel('Ages')
plt.ylabel('Median Salary (USD)')
plt.title('Median Salary (USD) by Age')
plt.show()

#Basic line graph using python module matplotlib

Example 2: add trendline to plot matplotlib

# plot the data itself
pylab.plot(x,y,'o')

# calc the trendline
z = numpy.polyfit(x, y, 1)
p = numpy.poly1d(z)
pylab.plot(x,p(x),"r--")
# the line equation:
print "y=%.6fx+(%.6f)"%(z[0],z[1])