How to plot a bar plot with matplotlib using two single values?

Question

I am trying to make a bar plot with two values for two classes A and B using matplotlib. My values are a = 43 and b = 21.

I need the plot to look like this:

I have been trying to do it almost an hour using matplotlib examples but eventually gave up. Maybe somebody can help me out?

Answer 1

As of mpl 1.5 you can simply do:

import matplotlib.pyplot as plt

fig, ax  = plt.subplots()
ax.bar([1, 2], [43, 21], width=1,
       tick_label=['A', 'B'], align='center')

Answer 2

Use bar():

import matplotlib.pyplot as plt

fig = plt.figure()
s = fig.add_subplot(111)
s.bar([1, 2], [43, 21], width=1)
s.set_xlim(0.5, 3.5)
fig.savefig('t.png')

Edit: following the specs more accurately.