Plotting a single latitude doesn't work

[bnlawrence]

Bug reported by @alaniwi.

[alaniwi]

Also observed with single longitude.

(This from a random CMIP6 file that happens to be in my directory. Filename is tas_Amon_MPI-ESM1-2-LR_historical_r1i1p1f1_gn_185001-186912.nc; I can find full URL on request.)

[bnlawrence]

Ok, I think I understand why this is happening. When we create the display we are using floats which are "window friendly", not actual integer array addresses. Sometimes this works, so when we have "longitude=77.0" there is an actual 77.0, but sometimes there is not - this is a version of the classic floating point equivalence problem. We need to fix the arguments in this statement to account for this: pfld = field.subspace(**subspace_kwargs).

[alaniwi]

@bnlawrence Seems plausible. This grid has longitude spacing 1.875 degrees, so in this case the longitude values themselves can be represented as exact binary fractions, but if rounded to 2 decimal places, then every other one will not work. And indeed, I find that 165 and 168.75 degrees east both work, but 166.88 does not.