Time units of 'months' or 'years' cause print() to ValueError

[samizdis]

If the units of a time coord are months or years, printing the cube fails with

ValueError: units must be one of 'seconds', 'minutes', 'hours' or 'days' (or singular version of these), got 'months'

It looks like this was addressed back in Feb (https://groups.google.com/forum/#!topic/scitools-iris/c8B75mRQ7JU), with two identically-named PRs (SciTools/cf-units#72 and #2354, one of which is merged, but this still breaks in v1.13.0

[djkirkham]

Thanks for raising this. We'll need to do a release of cf_units before #2354 can be merged, once that's done this issue will be fixed.

[rcomer]

Looks like #2354 fixed the printing of coordinates, but not the printing of a cube with a scalar time coordinate:

import iris

print(iris.__version__)

cube = iris.cube.Cube(1)
cube.add_aux_coord(iris.coords.DimCoord(1, standard_name='time', units='years since 2020-03-23'))

print(cube)

3.0.1
Traceback (most recent call last):
  File "print_cube_year_coord.py", line 8, in <module>
    print(cube)
  File "[site-packages-path]/iris/cube.py", line 2594, in __str__
    return self.summary()
  File "[site-packages-path]/iris/cube.py", line 2505, in summary
    coord_cell = coord.cell(0)
  File "[site-packages-path]/iris/coords.py", line 1904, in cell
    point = self.units.num2date(point)
  File "[site-packages-path]/cf_units/__init__.py", line 2026, in num2date
    cdf_utime = self.utime()
  File "[site-packages-path]/cf_units/__init__.py", line 1940, in utime
    raise ValueError(emsg.format(interval))
ValueError: Time units with interval of "months", "years" (or singular of these) cannot be processed, got "years".

[github-actions]

In order to maintain a backlog of relevant issues, we automatically label them as stale after 500 days of inactivity.

If this issue is still important to you, then please comment on this issue and the stale label will be removed.

Otherwise this issue will be automatically closed in 28 days time.

[rcomer]

SciTools/cf-units#279 may well address this. I vote we leave this open till that is done.

[github-actions]

In order to maintain a backlog of relevant issues, we automatically label them as stale after 500 days of inactivity.

If this issue is still important to you, then please comment on this issue and the stale label will be removed.

Otherwise this issue will be automatically closed in 28 days time.