"""

========

Colorbar

========

This example shows how to use colorbar by specifying the mappable object (here

the imshow returned object) and the axes to attach the colorbar to.

"""

import numpy as np

import matplotlib.pyplot as plt

# setup some generic data

N = 37

x, y = np.mgrid[:N, :N]

Z = (np.cos(x*0.2) + np.sin(y*0.3))

# mask out the negative and positve values, respectively

Zpos = np.ma.masked_less(Z, 0)

Zneg = np.ma.masked_greater(Z, 0)

fig, (ax1, ax2) = plt.subplots(figsize=(8, 3), ncols=2)

# plot just the positive data and save the

# color "mappable" object returned by ax1.imshow

pos = ax1.imshow(Zpos, cmap='Blues', interpolation='none')

# add the colorbar using the figure's method,

# telling which mappable we're talking about and

# which axes object it should be near

fig.colorbar(pos, ax=ax1)

# repeat everything above for the negative data

neg = ax2.imshow(Zneg, cmap='Reds_r', interpolation='none')

fig.colorbar(neg, ax=ax2)

plt.show()