Unit expection error Ephem.from_horizons

[kaya4me2]

High-level problem description
Getting a value error thrown after jupyter notebook cell run:

ValueError: 'hour' did not parse as unit: At col 0, hour is not a valid unit. If this is meant to be a custom unit, define it with 'u.def_unit'. To have it recognized inside a file reader or other code, enable it with 'u.add_enabled_units'. For details, see https://docs.astropy.org/en/latest/units/combining_and_defining.html

What did you do?

from sbpy.data import Ephem
import astropy.units as u
from astropy.time import Time

targets = ['2100', '2018 RC1', 'Ganymed']
eph = Ephem.from_horizons(targets, location=568,
epochs={'start': Time('2018-01-01'),
'stop': Time('2018-02-01'),
'step':1*u.hour})

eph.table

What did you expect?

Should reproduce table as demonstrated in tutorial

https://github.com/NASA-Planetary-Science/sbpy-tutorial/blob/main/notebooks/data/Ephem.ipynb

What did really happen?
What is the actual result of the code snippet?

---

ValueError Traceback (most recent call last)
File ~/anaconda3/envs/sbpy/lib/python3.11/site-packages/astropy/units/format/generic.py:587, in Generic._do_parse(cls, s, debug)
584 try:
585 # This is a short circuit for the case where the string
586 # is just a single unit name
--> 587 return cls._parse_unit(s, detailed_exception=False)
588 except ValueError as e:

File ~/anaconda3/envs/sbpy/lib/python3.11/site-packages/astropy/units/format/generic.py:483, in Generic._parse_unit(cls, s, detailed_exception)
482 else:
--> 483 raise ValueError()

ValueError:

During handling of the above exception, another exception occurred:

ValueError Traceback (most recent call last)
File ~/anaconda3/envs/sbpy/lib/python3.11/site-packages/astropy/units/format/generic.py:453, in Generic._get_unit(cls, t)
452 try:
--> 453 return cls._parse_unit(t.value)
454 except ValueError as e:

File ~/anaconda3/envs/sbpy/lib/python3.11/site-packages/astropy/units/format/generic.py:481, in Generic._parse_unit(cls, s, detailed_exception)
480 if detailed_exception:
--> 481 raise ValueError(f"{s} is not a valid unit. {did_you_mean(s, registry)}")
482 else:

ValueError: hour is not a valid unit.

During handling of the above exception, another exception occurred:

ValueError Traceback (most recent call last)
File ~/anaconda3/envs/sbpy/lib/python3.11/site-packages/astropy/units/core.py:2098, in _UnitMetaClass.call(self, s, represents, format, namespace, doc, parse_strict)
2097 try:
-> 2098 return f.parse(s)
2099 except NotImplementedError:

File ~/anaconda3/envs/sbpy/lib/python3.11/site-packages/astropy/units/format/generic.py:571, in Generic.parse(cls, s, debug)
569 s = cls._regex_deg.sub(cls._convert_deg, s)
--> 571 result = cls._do_parse(s, debug=debug)
572 # Check for excess solidi, but exclude fractional exponents (accepted)

File ~/anaconda3/envs/sbpy/lib/python3.11/site-packages/astropy/units/format/generic.py:590, in Generic._do_parse(cls, s, debug)
589 try:
--> 590 return cls._parser.parse(s, lexer=cls._lexer, debug=debug)
591 except ValueError as e:

File ~/anaconda3/envs/sbpy/lib/python3.11/site-packages/astropy/utils/parsing.py:116, in ThreadSafeParser.parse(self, *args, **kwargs)
115 with self._lock:
--> 116 return self.parser.parse(*args, **kwargs)

File ~/anaconda3/envs/sbpy/lib/python3.11/site-packages/astropy/extern/ply/yacc.py:333, in LRParser.parse(self, input, lexer, debug, tracking, tokenfunc)
332 else:
--> 333 return self.parseopt_notrack(input, lexer, debug, tracking, tokenfunc)

File ~/anaconda3/envs/sbpy/lib/python3.11/site-packages/astropy/extern/ply/yacc.py:1063, in LRParser.parseopt_notrack(self, input, lexer, debug, tracking, tokenfunc)
1062 if not lookaheadstack:
-> 1063 lookahead = get_token() # Get the next token
1064 else:

File ~/anaconda3/envs/sbpy/lib/python3.11/site-packages/astropy/extern/ply/lex.py:350, in Lexer.token(self)
348 self.lexpos = lexpos
--> 350 newtok = func(tok)
352 # Every function must return a token, if nothing, we just move to next token

File ~/anaconda3/envs/sbpy/lib/python3.11/site-packages/astropy/units/format/generic.py:123, in Generic._make_lexer..t_UNIT(t)
122 "%|([YZEPTGMkhdcmu\N{MICRO SIGN}npfazy]?'((?!\d)\w)+')|((?!\d)\w)+"
--> 123 t.value = cls._get_unit(t)
124 return t

File ~/anaconda3/envs/sbpy/lib/python3.11/site-packages/astropy/units/format/generic.py:459, in Generic._get_unit(cls, t)
457 return registry.aliases[t.value]
--> 459 raise ValueError(f"At col {t.lexpos}, {str(e)}")

ValueError: At col 0, hour is not a valid unit.

During handling of the above exception, another exception occurred:

ValueError Traceback (most recent call last)
Cell In[19], line 6
3 from astropy.time import Time
5 targets = ['2100', '2018 RC1', 'Ganymed']
----> 6 eph = Ephem.from_horizons(targets, location=568,
7 epochs={'start': Time('2018-01-01'),
8 'stop': Time('2018-02-01'),
9 'step':1*u.hour})
11 eph.table

File ~/anaconda3/envs/sbpy/lib/python3.11/site-packages/sbpy/utils/decorators.py:78, in requires..decorator..wrapper(*func_args, **func_kwargs)
75 except RequiredPackageUnavailable as exc:
76 # trim a couple levels of the traceback to clean up error messages
77 raise exc.with_traceback(exc.traceback.tb_next.tb_next)
---> 78 return wrapped_function(*func_args, **func_kwargs)

File ~/anaconda3/envs/sbpy/lib/python3.11/site-packages/sbpy/bib/core.py:183, in cite..decorator..wrapper(*args, **kwargs)
180 @wraps(f)
181 def wrapper(*args, **kwargs):
182 # only cite after successful call
--> 183 result = f(*args, **kwargs)
184 register(f, citations)
185 return result

File ~/anaconda3/envs/sbpy/lib/python3.11/site-packages/sbpy/data/ephem.py:239, in Ephem.from_horizons(cls, targetids, id_type, epochs, location, **kwargs)
236 all_eph['epoch'] = Time(all_eph['datetime_jd'], format='jd',
237 scale='utc')
238 if 'siderealtime' in all_eph.colnames:
--> 239 all_eph['siderealtime'].unit = u.Unit('hour')
241 all_eph.remove_column('datetime_jd')
242 all_eph.remove_column('datetime_str')

File ~/anaconda3/envs/sbpy/lib/python3.11/site-packages/astropy/units/core.py:2121, in _UnitMetaClass.call(self, s, represents, format, namespace, doc, parse_strict)
2111 msg = (
2112 f"'{s}' did not parse as {format_clause}unit: {str(e)} "
2113 "If this is meant to be a custom unit, "
(...)
2118 "https://docs.astropy.org/en/latest/units/combining_and_defining.html"
2119 )
2120 if parse_strict == "raise":
-> 2121 raise ValueError(msg)
2122 elif parse_strict == "warn":
2123 warnings.warn(msg, UnitsWarning)

ValueError: 'hour' did not parse as unit: At col 0, hour is not a valid unit. If this is meant to be a custom unit, define it with 'u.def_unit'. To have it recognized inside a file reader or other code, enable it with 'u.add_enabled_units'. For details, see https://docs.astropy.org/en/latest/units/combining_and_defining.html

Provide information on your environment:

print(mpl.version)
print(specutils.version)
print(scipy.version)
print(sbpy.version)
print(astropy.version)
print(np.version)
print(astroquery.version)

3.8.0
1.11.0
1.11.4
0.5.0
5.3.4
1.26.3
0.4.6

M3 MacOSX 14.2.1

[mkelley]

That astropy cannot parse the string 'hour' as a unit surprises me. I'm not able to reproduce this error, even after creating a clean environment with the same package versions:

astropy==5.3.4
astroquery==0.4.6
matplotlib==3.8.0
numpy==1.26.3
sbpy==0.5.0
scipy==1.11.4
specutils==1.11.0

Does the following code run for you?

import astropy.units as u
u.Unit('hour')

Or, perhaps try running the tutorial with a clean, isolated virtual environment and sbpy installed via pip install sbpy[recommended]?

[kaya4me2]

found the potential source of the curious error ... there was a cell in the notebook: *from astropy.units import cdscds.enable()* if this cell is run then one gets the ValueError: hourangle is not a valid unit.

…

On Mon, Sep 16, 2024 at 3:02 PM Michael Kelley ***@***.***> wrote: That astropy cannot parse the string 'hour' as a unit surprises me. I'm not able to reproduce this error, even after creating a clean environment with the same package versions: astropy==5.3.4 astroquery==0.4.6 matplotlib==3.8.0 numpy==1.26.3 sbpy==0.5.0 scipy==1.11.4 specutils==1.11.0 Does the following code run for you? import astropy.units as u u.Unit('hour') Or, perhaps try running the tutorial with a clean, isolated virtual environment and sbpy installed via pip install sbpy[recommended]? — Reply to this email directly, view it on GitHub <#414 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AQ5PTL2UINOW3OB3BS7P5D3ZW42NRAVCNFSM6AAAAABOJR2JT6VHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDGNJTHAYDKOJVGE> . You are receiving this because you authored the thread.Message ID: ***@***.***>

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[mkelley]

Ah, that makes sense!