Q:

How can colour bar scales be shared amongst subplots?

I have the following code:
f, ax = plt.subplots(1,2, figsize=(20,20))
divider = make_axes_locatable(ax[0])
cax = divider.append_axes("right", size="5%", pad=0.1)
#level_geo.boundary.plot(ax=ax[0], color='black')
level_geo.plot(ax=ax[0], cmap='viridis', column='dem_2001', legend=True, cax=cax)

divider = make_axes_locatable(ax[1])
cax = divider.append_axes("right", size="5%", pad=0.1)
#level_geo.boundary.plot(ax=ax[1], color='black')
level_geo.plot(ax=ax[1], cmap='viridis', column='dem_2030', legend=True, cax=cax)

plt.show()

I am wondering how I share the colour bars so that there is just one bar with a scale relevant to both plots?

A:

If you want just a linear color map, you can just pass vmin and vmax to both plots.
f, ax = plt.subplots(1,2, figsize=(20,20))
divider = make_axes_locatable(ax[0])
cax = divider.append_axes("right", size="5%", pad=0.1)
#level_geo.boundary.plot(ax=ax[0], color='black')
level_geo.plot(ax=ax[0], cmap='viridis', column='dem_2001', legend=True, cax=cax, vmin=0, vmax=1)

divider = make_axes_locatable(ax[1])
cax = divider.append_axes("right", size="5%", pad=0.1)
#level_geo.boundary.plot(ax=ax[1], color='black')
level_geo.plot(ax=ax[1], cmap='viridis', column='dem_2030', legend=True, cax=cax, vmin=0, vmax=1)

plt.show()

Or, better, use min and max retrieved from the data (e.g. level_geo['dem_2030'].min())

