import os
import numpy as np
import matplotlib.pyplot as plt

# Generate dummy data
delta = 0.01
x = np.arange(-3.0, 3.0, delta)
y = np.arange(-3.0, 3.0, delta)
X, Y = np.meshgrid(x, y)
Z = X * Y

# Set range and steps for colour bar
c_max = 8
c_min = -8
c_step = 2

# Create colour map
cmap = plt.cm.get_cmap('Blues', (c_max - c_min + c_step) / c_step)

fig, ax = plt.subplots(1, 1, figsize=(6, 4))

# Plot image
im = ax.imshow(Z,
               cmap=cmap,
               interpolation='bilinear',
               vmax=c_max + c_step / 2,
               vmin=c_min - c_step / 2)

# Add colour bar
plt.colorbar(im, ticks=np.arange(c_min, c_max + 1, c_step))

# Hide spines and ticks
ax.set_axis_off()

# Export figure
png_name = os.path.join(
    'png',
    os.path.basename(__file__).replace('.py', '.png').replace('_', '-'))
plt.savefig(png_name, bbox_inches='tight', dpi=100)