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tight_layout() doesn't work properly on plots with a WCSAxes projection #8703
Description
A Matpltolib Axes created with projection=wcs does not play well with Matplotlib's tight_layout() method, that is supposed to re-size elements of a figure such that there are no overlapping labels/axes etc.
Consdier the following example:
import matplotlib.pyplot as plt
from astropy.wcs import WCS
from astropy.io import fits
from astropy.utils.data import get_pkg_data_filename
filename = get_pkg_data_filename('galactic_center/gc_msx_e.fits')
hdu = fits.open(filename)[0]
wcs = WCS(hdu.header)
fig = plt.figure(figsize=(8, 6))
n = 2
for i in range(n):
projection = wcs
# projection = None
plt.subplot(n, 1, i + 1, projection=projection)
# plt.imshow(hdu.data, vmin=-2.e-5, vmax=2.e-4, origin='lower')
plt.grid(color='white', ls='solid')
plt.xlabel('Galactic Longitude')
plt.ylabel('Galactic Latitude')
plt.title('WCSAxes plot')
fig.tight_layout()
plt.show()projection=None, no tight_layout:
projection=None, with tight_layout:
(note how this re-organises things nicely)
projection='wcs', no tight_layout:
projection='wcs', with tight_layout:
Note how things actually get worse!
- astropy 3.1.2
- Matplotlib 3.0.3
Activity
pllim commentedon May 15, 2019
Is this related to #8678 (comment) ?
dstansby commentedon May 15, 2019
I don't think so, that is only a problem on Matplotlib dev (post version
3.0.3), whereas this is an issue on a version of Maptlotlib (3.0.3) that predates that change.astrofrog commentedon May 15, 2019
I have some ideas :)
astrofrog commentedon May 17, 2019
A workaround for now is to call:
before
Basically the fundamental issue is that
get_tightbboxactually requires the figure to be drawn once before it returns correct results. We should probably find a way to avoid this - but in the mean time we could overloadtight_layoutinWCSAxesand just force a draw first.dstansby commentedon Oct 4, 2020
For reference, some simpler code to reproduce this:
dstansby commentedon Oct 5, 2020
As I slowly descend into madness trying to work this out, a note that the end goal to get this working is to have
TickLabelsandAxisLabelshave their ownget_tight_bbox()methods that can calculate their own Bboxes. This is going to need a lot of refactoring, but I suspect in the long run it should significantly tidy up the WCSAxes code.