Issue generating beams

[jpinedaf]

I am using the latest version: radio-beam-0.3.8.dev12+g325cad3

I am trying to generate a simple circular beam as this:

import astropy.units as u
from radio_beam import Beam

bmaj = 14 * u.arcsec
bmin = 14 * u.arcsec
bpa = 0.0 * u.deg

beam = Beam(major=bmaj, minor=bmin, pa=bpa)

but I get the following error message

Cell In[40], line 8
      5 bmin = 14 * u.arcsec
      6 bpa = 0.0 * u.deg
----> 8 beam = Beam(major=bmaj, minor=bmin, pa=bpa)

File ~/code/python_code/radio_beam/radio_beam/beam.py:86, in Beam.__new__(cls, major, minor, pa, area, default_unit, meta)
     84         minor = minor * u.deg
     85 if pa is not None:
---> 86     if u.deg.is_equivalent(pa):
     87         pa = pa
     88     else:

File ~/miniconda3/envs/astro/lib/python3.11/site-packages/astropy/units/core.py:1013, in UnitBase.is_equivalent(self, other, equivalencies)
   1009     return any(self.is_equivalent(u, equivalencies) for u in other)
   1011 other = Unit(other, parse_strict="silent")
-> 1013 return self._is_equivalent(other, equivalencies)

File ~/miniconda3/envs/astro/lib/python3.11/site-packages/astropy/units/core.py:1024, in UnitBase._is_equivalent(self, other, equivalencies)
   1021 if isinstance(other, UnrecognizedUnit):
   1022     return False
-> 1024 if self._get_physical_type_id() == other._get_physical_type_id():
   1025     return True
   1026 elif len(equivalencies):

File ~/miniconda3/envs/astro/lib/python3.11/site-packages/astropy/units/core.py:695, in UnitBase._get_physical_type_id(self)
    688 """
    689 Returns an identifier that uniquely identifies the physical
    690 type of this unit.  It is comprised of the bases and powers of
    691 this unit, without the scale.  Since it is hashable, it is
    692 useful as a dictionary key.
    693 """
    694 if self._type_id is None:
--> 695     unit = self.decompose()
    696     self._type_id = tuple(zip((base.name for base in unit.bases), unit.powers))
    698 return self._type_id

File ~/miniconda3/envs/astro/lib/python3.11/site-packages/astropy/units/core.py:2485, in CompositeUnit.decompose(self, bases)
   2482         self._decomposed_cache = self
   2483     return self
-> 2485 x = CompositeUnit(
   2486     self.scale, self.bases, self.powers, decompose=True, decompose_bases=bases
   2487 )
   2488 if len(bases) == 0:
   2489     self._decomposed_cache = x

File ~/miniconda3/envs/astro/lib/python3.11/site-packages/astropy/units/core.py:2358, in CompositeUnit.__init__(self, scale, bases, powers, decompose, decompose_bases, _error_check)
   2356 if _error_check:
   2357     if scale == 0:
-> 2358         raise UnitScaleError("cannot create a unit with a scale of 0.")
   2359     for base in bases:
   2360         if not isinstance(base, UnitBase):

UnitScaleError: cannot create a unit with a scale of 0.

In [41]: 

It all gets solved if I use a PA different from 0

In [41]: import astropy.units as u
    ...: from radio_beam import Beam
    ...: 
    ...: bmaj = 14 * u.arcsec
    ...: bmin = 14 * u.arcsec
    ...: bpa = 1.0 * u.deg
    ...: 
    ...: beam = Beam(major=bmaj, minor=bmin, pa=bpa)

In [42]: 

Is there something wrong with what I am doing?

[e-koch]

thanks @jpinedaf! This will be fixed with #128.

[jpinedaf]

yes, this works! Thanks