odd (wrong?) desiname

[moustakas]

@akremin

>>> from desiutil.names import radec_to_desiname
>>> radec_to_desiname(40.669625, -0.013277777)
array(['DESI J040.6696000.-132'], dtype='<U22')

I think we've hit a corner-case that the algorithm gets wrong. Haven't checked any catalogs yet; I came across this in the wild.

[weaverba137]

When the numbers are truncated, precision == 4:

>>> dectrunc = np.trunc((10 ** precision) * target_dec).astype(int).astype(str)
>>> dectrunc
'-132'

which isn't enough characters to properly handle the zero-padding below that point. If the zero-padding were performed immediately after, then it might work.

>>> dectrunc.zfill(7)
'-000132'
>>> dectrunc.zfill(7)[:-precision] + '.' + dectrunc.zfill(7)[-precision:]
'-00.0132'

[weaverba137]

Please take a look at this updated code. I've added some tests for when RA or Dec are very close to zero.

[moustakas]

That update looks great, @weaverba137, thanks for the quick turn-around.

[akremin]

Thank you for the quick update, Ben. A very nice and clean solution! I think that the solution using 7 and 6 zero padding is specific to precision=4. The level of precision is a variable but is not an input argument, so this is a very minor issue. At some point we should update it though.

[weaverba137]

@akremin, I agree, I'll make the padding a function of precision to make that explicit.