BUG: Subplot data is lost when sharex=True and latter DatetimeIndex has higher frequency

[jluttine]

Pandas version checks

• I have checked that this issue has not already been reported.

• I have confirmed this bug exists on the latest version of pandas.

• I have confirmed this bug exists on the main branch of pandas.

Reproducible Example

import matplotlib.pyplot as plt
import numpy as np
import pandas as pd

(_, axs) = plt.subplots(2, 1, sharex=True)

t0 = pd.date_range("2023-09-12 10:00", periods=48, freq="1H")
t1 = pd.date_range("2023-09-12 10:00", periods=12*48, freq="5Min")

x0 = pd.Series(
    index=t0,
    data=np.random.randn(48),
)
x1 = pd.Series(
    index=t1,
    data=np.random.randn(12*48),
)

x0.plot(ax=axs[0])
x1.plot(ax=axs[1])

Issue Description

When using subplots and sharing x axis, if a latter plot has a higher temporal resolution, the former plot gets emptied.

(Sorry, I checked the box that I've tested with the latest version of pandas but unfortunately I was able to test only 2.0.3 for now. I'll see if I can manage to test 2.1.0 some other day perhaps.)

Expected Behavior

Both plots should show data:

Installed Versions

INSTALLED VERSIONS

commit : 0f43794
python : 3.11.4.final.0
python-bits : 64
OS : Linux
OS-release : 6.3.3
Version : #1-NixOS SMP PREEMPT_DYNAMIC Wed May 17 12:02:08 UTC 2023
machine : x86_64
processor :
byteorder : little
LC_ALL : None
LANG : en_US.UTF-8
LOCALE : en_US.UTF-8

pandas : 2.0.3
numpy : 1.25.1
pytz : 2023.3
dateutil : 2.8.2
setuptools : 67.4.0.post0
pip : None
Cython : 0.29.36
pytest : 7.4.0
hypothesis : 6.68.2
sphinx : 5.3.0
blosc : None
feather : None
xlsxwriter : None
lxml.etree : None
html5lib : 1.1
pymysql : None
psycopg2 : 2.9.5
jinja2 : 3.1.2
IPython : 8.11.0
pandas_datareader: None
bs4 : 4.12.2
bottleneck : None
brotli : 1.0.9
fastparquet : None
fsspec : None
gcsfs : None
matplotlib : 3.7.2
numba : None
numexpr : 2.8.4
odfpy : None
openpyxl : None
pandas_gbq : None
pyarrow : None
pyreadstat : None
pyxlsb : None
s3fs : None
scipy : 1.11.1
snappy : None
sqlalchemy : 2.0.19
tables : 3.8.0
tabulate : None
xarray : None
xlrd : None
zstandard : None
tzdata : 2022.7
qtpy : None
pyqt5 : None

[paulreece]

Hey there, I was attempting to run your test script on 2.1.0 but it's not actually rendering any plots, I only get <Axes: > as a return value for each call to plot().

[jluttine]

Ok, before the plotting commands, try running:

plt.ion()

Does that help?

[paulreece]

Does that help?

Unfortunately no.
To be clear I ran this as a separate script as well as in the REPL.
Here's my REPL output:

>>> import matplotlib.pyplot as plt
>>> import numpy as np
>>> import pandas as pd
>>> (_, axs) = plt.subplots(2, 1, sharex=True)
>>> t0 = pd.date_range("2023-09-12 10:00", periods=48, freq="1H")
>>> t1 = pd.date_range("2023-09-12 10:00", periods=12*48, freq="5Min")
>>> x0 = pd.Series(
...     index=t0,
...     data=np.random.randn(48),
... )
>>> x1 = pd.Series(
...     index=t1,
...     data=np.random.randn(12*48),
... )
>>> plt.ion()
<contextlib.ExitStack object at 0x144769c50>
>>> x0.plot(ax=axs[0])
<Axes: >
>>> x1.plot(ax=axs[1])
<Axes: >

[jluttine]

How about plt.show() after plotting? (And no plt.ion())

[paulreece]

That did it!

I can confirm the bug is occurring on the main branch 2.1.0

[azjps]

This is related to #52895 (and the other issues linked in #52895 (comment)), the issue is that pandas plots periodic datetime ranges in a different unit (which will work okay if nothing else is changed about the plot, but once there are multiple axes/plots involved or any other matplotlib date utilites are used, everything breaks down). It seems to look okay after fixed to not plot in different units: