Harmonize tick-resolution-choosing and tick-format-choosing logic

[spencerkclark]

The code that chooses the resolution of the ticks and the code that chooses the format of the ticks are sometimes not consistent with each other. This can lead to confusing axis tick labels, e.g. in the following example provided by @klindsay28:

import cftime
import matplotlib.pyplot as plt
import nc_time_axis

time_vals = [cftime.DatetimeNoLeap(1+year, 1+month, 15)
             for year in range(3) for month in range(12)]

x_vals = [time_val.year + time_val.dayofyr / 365.0
          for time_val in time_vals]

fig, ax = plt.subplots(1, 1)
ax.plot(time_vals, x_vals, "-o")

In this case a monthly resolution is chosen for the ticks, but a tick format of "%Y" is used, giving the false impression that the ticks represent the beginning of years. I would expect for monthly resolution ticks, a format of "%Y-%m" would be used. In this example this would result in a plot that looked like this:

If possible it would be great if we could make sure that inconsistencies like the above example could be avoided.

xref: pydata/xarray#4401

[bjlittle]

@spencerkclark Is this still a live issue that we want to pull into v1.3.0 ?

[spencerkclark]

Yes, this is still a live issue and would be great to fix someday. I think it can wait until a future nc-time-axis release, however, since it involves a little more than just catching up with changes in upstream packages.

[bjlittle]

@spencerkclark Awesome. Okay, agreed 👍

I'm going to create a 1.4.0 milestone, project and GH discussion, so that we can easily triage all such issues and PRs, and it'll help slowly shape the content of the next, next release 😉

[spencerkclark]

Closed by #79.