poliastro.twobody.Orbit import error

[ReeceHumphreys]

Importing Orbit from poliastro.twobody results in an attribute error.

🐞 Problem

On macOS 12.3, I performed an install using pip and the instructions for downloading the latest build from GitHub and am getting an attribute error when importing Orbit as follows:

from poliastro.twobody import Orbit

Here is the resulting Attribute error that got output:

AttributeError                            Traceback (most recent call last)
/Users/reecehumphreys/Developer/Personal/ODAP/notebooks/Introduction.ipynb Cell 27' in <cell line: [1]()>()
----> 1[ from poliastro.twobody import Orbit

File ~/.virtualenvs/odap/lib/python3.9/site-packages/poliastro/twobody/__init__.py:1, in <module>
----> ]()[1]()[ from poliastro.twobody.orbit import Orbit
      ]()[3]()[ __all__ = ["Orbit"]

File ~/.virtualenvs/odap/lib/python3.9/site-packages/poliastro/twobody/orbit/__init__.py:1, in <module>
----> ]()[1]()[ from poliastro.twobody.orbit.scalar import Orbit
      ]()[3]()[ __all__ = ["Orbit"]

File ~/.virtualenvs/odap/lib/python3.9/site-packages/poliastro/twobody/orbit/scalar.py:6, in <module>
      ]()[4]()[ import numpy as np
      ]()[5]()[ from astropy import time, units as u
----> ]()[6]()[ from astropy.coordinates import (
      ]()[7]()[     ICRS,
      ]()[8]()[     CartesianDifferential,
      ]()[9]()[     CartesianRepresentation,
     ]()[10]()[     get_body_barycentric,
     ]()[11]()[ )
     ]()[13]()[ from poliastro.frames.util import get_frame
     ]()[14]()[ from poliastro.threebody.soi import laplace_radius

File ~/.virtualenvs/odap/lib/python3.9/site-packages/astropy/coordinates/__init__.py:16, in <module>
     ]()[14]()[ from .earth import *
     ]()[15]()[ from .transformations import *
---> ]()[16]()[ from .builtin_frames import *
     ]()[17]()[ from .name_resolve import *
     ]()[18]()[ from .matching import *

File ~/.virtualenvs/odap/lib/python3.9/site-packages/astropy/coordinates/builtin_frames/__init__.py:32, in <module>
     ]()[30]()[ from .fk4 import FK4, FK4NoETerms
     ]()[31]()[ from .galactic import Galactic
---> ]()[32]()[ from .galactocentric import Galactocentric, galactocentric_frame_defaults
     ]()[33]()[ from .supergalactic import Supergalactic
     ]()[34]()[ from .altaz import AltAz

File ~/.virtualenvs/odap/lib/python3.9/site-packages/astropy/coordinates/builtin_frames/galactocentric.py:591, in <module>
    ]()[587]()[     return get_matrix_vectors(galactocentric_coord, inverse=True)
    ]()[590]()[ # Create loopback transformation
--> ]()[591]()[ frame_transform_graph._add_merged_transform(Galactocentric, ICRS, Galactocentric)

AttributeError: 'TransformGraph' object has no attribute '_add_merged_transform']()

This seems to be an issue with AstroPy looking at the stack trace but I figured that I would bring it to your attention!

[astrojuanlu]

Hello @ReeceHumphreys , thanks for opening this issue! Indeed, it looks like we're incompatible with the latest Astropy. Could you please try pip install "astropy<5" and try again?

[ReeceHumphreys]

Hello @astrojuanlu , that fixed the issue!

[astrojuanlu]

Thanks for checking! We'll need to do a bugfix release, it will happen in a few months.

[yakkonaut]

Linking #1496 here. Going to start taking a look at this. Will post to the matrix server too- I don't want to duplicate anyone's effort but happy to take a swing at the update here.

[kerel-fs]

Thanks @yakkonaut for cross-linking this issue! I failed to find it during my previous search when investigating the version pin for astropy.

---

With a local checkout of branch 0.16.x I can't reproduce the import issue for poliastro.twobody.Orbit stated here.

Steps performed:

• Checkout branch 0.16.x
• Modify version pinning in pyproject.toml to astropy>=5
• Install via pip install -e .
• Run this code: from poliastro.twobody import Orbit --> no import error

Running tox -e py310-fast succeeds as well, see tox_py310-fast.log.

[astrojuanlu]

Thanks all for checking this. Perhaps this was a temporary problem that got fixed in a subsequent Astropy release, but I can't find any references to it in the Astropy tracker. If it disappeared, we can close and just remove the pinning in 0.16.1.

[astrojuanlu]

Hopefully #1501 fixes this, please have a look.

[astrojuanlu]

Closed in poliastro 0.16.3 🚀