WCSAxes and shared axis

I am trying to plot a figure with several WCSAxes where I would like to have the sharex/sharey feature working. The basic example would be:

import numpy as np
from matplotlib import pyplot as plt
from astropy.io.fits import ImageHDU
from astropy.wcs import WCS
plt.ion()

# Same physical region on the sky
HDUs = []
for index in range(3):
    npix = (index+1)*2+1
    this_map  = np.zeros((npix, npix))
    this_map[1,1] = 1

    w = WCS(naxis=2)
    w.wcs.crpix = [(npix+1)/2, (npix+1)/2]
    w.wcs.cdelt = [3./npix, 3./npix]
    HDUs.append(ImageHDU(this_map, w.to_header()))

# Proper figure without shared axis
fig = plt.figure()
for index, hdu in enumerate(HDUs):
    if index == 0:
        ax_ref = fig.add_subplot(len(HDUs), 1, index+1,
                                 projection=WCS(hdu.header))
        ax_ref.imshow(hdu.data)
    else:
        ax = fig.add_subplot(len(HDUs), 1, index+1,
                             projection=WCS(hdu.header))
        ax.imshow(hdu.data)

# Failing figure with shared axes
fig = plt.figure()
for index, hdu in enumerate(HDUs):
    if index == 0:
        ax_ref = fig.add_subplot(len(HDUs), 1, index+1,
                                 projection=WCS(hdu.header))
        ax_ref.imshow(hdu.data)
    else:
        ax = fig.add_subplot(len(HDUs), 1, index+1,
                             projection=WCS(hdu.header),
                             sharex=ax_ref, sharey=ax_ref)
        ax.imshow(hdu.data)

But unfortunately it seems that the sharex sharey keyword only applied on the pixel scale. Is there a way to make it work on world coordinates ?

[dstansby]

No, it doesn’t. The axes are shared on a ‘pixel’ level, not a ‘world coordinate’ level. To fix this issue they would need to be shared on a ‘world coordinate’ level.

[pllim]

Would @dstansby 's code above resolve the original question? Can we close this issue? Thanks!