for y in np.arange(r_sweep):
    z = Z[:, (y)]
ax.bar(xs, z, zs=y, zdir='y', alpha=0.8)
ax.set_xlabel('biopsies')
ax.set_ylabel('radius of biopsy')
ax.set_zlabel('Shannon Index')
plt.show()
plotting 3d histogram/barplot in python matplotlib