Writing numerical values on the plot with Matplotlib

Use pyplot.text() (import matplotlib.pyplot as plt)

import matplotlib.pyplot as plt

x=[1,2,3]
y=[9,8,7]

plt.plot(x,y)
for a,b in zip(x, y): 
    plt.text(a, b, str(b))
plt.show()

You can use the annotate command to place text annotations at any x and y values you want. To place them exactly at the data points you could do this

import numpy
from matplotlib import pyplot

x = numpy.arange(10)
y = numpy.array([5,3,4,2,7,5,4,6,3,2])

fig = pyplot.figure()
ax = fig.add_subplot(111)
ax.set_ylim(0,10)
pyplot.plot(x,y)
for i,j in zip(x,y):
    ax.annotate(str(j),xy=(i,j))

pyplot.show()

If you want the annotations offset a little, you could change the annotate line to something like

ax.annotate(str(j),xy=(i,j+0.5))