Inset Locator Demo

import matplotlib.pyplot as plt

from mpl_toolkits.axes_grid1.inset_locator import inset_axes, zoomed_inset_axes
from mpl_toolkits.axes_grid1.anchored_artists import AnchoredSizeBar


def add_sizebar(ax, size):
    asb = AnchoredSizeBar(ax.transData,
                          size,
                          str(size),
                          loc=8,
                          pad=0.1, borderpad=0.5, sep=5,
                          frameon=False)
    ax.add_artist(asb)


fig, (ax, ax2) = plt.subplots(1, 2, figsize=[5.5, 3])

# first subplot
ax.set_aspect(1)

axins = inset_axes(ax,
                   width="30%",  # width = 30% of parent_bbox
                   height=1.,  # height : 1 inch
                   loc=3)

plt.xticks(visible=False)
plt.yticks(visible=False)


# second subplot
ax2.set_aspect(1)

axins = zoomed_inset_axes(ax2, zoom=0.5, loc='upper right')
# fix the number of ticks on the inset axes
axins.yaxis.get_major_locator().set_params(nbins=7)
axins.xaxis.get_major_locator().set_params(nbins=7)

plt.xticks(visible=False)
plt.yticks(visible=False)

add_sizebar(ax2, 0.5)
add_sizebar(axins, 0.5)

plt.draw()
plt.show()