how to install trident

Hum Chand
  • 1
  • 21 Jul '23

I want to shoot sightlines in TNG simulation, I installed trident for that using PIP install trident but after I do " import trident" in python environment I am getting an error

NameError                                 Traceback (most recent call last)
/opt/conda/lib/python3.6/site-packages/unyt/ in parse_unyt_expr(unit_expr)
     92         unit_expr = parse_expr(
---> 93             unit_expr, global_dict=global_dict, transformations=unit_text_transform
     94         )

/opt/conda/lib/python3.6/site-packages/sympy/parsing/ in parse_expr(s, local_dict, transformations, global_dict, evaluate)
--> 894     return eval_expr(code, local_dict, global_dict)

/opt/conda/lib/python3.6/site-packages/sympy/parsing/ in eval_expr(code, local_dict, global_dict)
    806     expr = eval(
--> 807         code, global_dict, local_dict)  # take local objects in preference

<string> in <module>

NameError: name 'μSymbol' is not defined

During handling of the above exception, another exception occurred:

UnitParseError                            Traceback (most recent call last)
<ipython-input-7-306c42f8c86a> in <module>
----> 1 import trident

/opt/conda/lib/python3.6/site-packages/trident/ in <module>
     20 # Must run import_check() before anything else is imported to avoid
     21 # astropy error when importing trident in trident package directory
---> 22 from trident.utilities import import_check
     23 import_check()

/opt/conda/lib/python3.6/site-packages/trident/ in <module>
     19 import tempfile
     20 import shutil
---> 21 from yt.funcs import \
     22     get_pbar
     23 import numpy as np

/opt/conda/lib/python3.6/site-packages/yt/ in <module>
     10 __version__ = "4.0.5"
---> 12 import yt.units as units
     13 import yt.utilities.physical_constants as physical_constants
     14 from yt.data_objects.api import (

/opt/conda/lib/python3.6/site-packages/yt/units/ in <module>
----> 1 from unyt.array import (
      2     loadtxt,
      3     savetxt,
      4     uconcatenate,
      5     ucross,

/opt/conda/lib/python3.6/site-packages/unyt/ in <module>
     73 from ._version import get_versions
---> 75 from unyt import unit_symbols
     76 from unyt import physical_constants

/opt/conda/lib/python3.6/site-packages/unyt/ in <module>
     31 for _canonical_name, _alt_names in _name_alternatives.items():
     32     for _alt_name in _alt_names:
---> 33         _namespace[_alt_name] = _Unit(_canonical_name, registry=_registry)

/opt/conda/lib/python3.6/site-packages/unyt/ in __new__(cls, unit_expr, base_value, base_offset, dimensions, registry, latex_repr)
    222                 return registry._unit_object_cache[unit_expr]
    223             unit_cache_key = unit_expr
--> 224             unit_expr = parse_unyt_expr(unit_expr)
    225         # Make sure we have an Expr at this point.
    226         if not isinstance(unit_expr, Expr):

/opt/conda/lib/python3.6/site-packages/unyt/ in parse_unyt_expr(unit_expr)
     98             repr(e),
     99         )
--> 100         raise UnitParseError(msg)
    101     return unit_expr

UnitParseError: Unit expression 'µm' raised an error during parsing:
NameError("name 'μSymbol' is not defined",)

when I do this on my local PC it works fine but I can't do analysis on the local PC because of the large file size, I don't have that much space. Alternatively, I am using the fake spectra python library but Trident is more sophisticated so wanted to switch to it.

Dylan Nelson
  • 21 Jul '23

If I had to guess, I would say that there is some version issue, maybe Python 3.6 is too old for this purpose. Ideally the package would tell you. I can't offer more than that, you could ask over at the Trident site whether someone has seen a similar error.

Hum Chand
  • 21 Jul '23

Thanks for the reply, Is there any way to update Python in the remote jupyter lab interface, I guess it's a problem with the Sympy package which is not able to get updated to the latest version when I install Trident. Also I cannot upgrade sympy too .
Thanks for the help.

Dylan Nelson
  • 21 Jul '23

You could try to set up a new python installation using e.g. miniconda, inside the Lab.

Hum Chand
  • 21 Jul '23

ok, thank you so much!

Hum Chand
  • 1
  • 21 Jul '23

Ok so following your advice I was able to install Trident and it is working!
here is how to do it if anyone else is trying the same -
(The problem is the old version of Python so we need to install the newest version )
First install miniconda by running the following command in the terminal

mkdir -p ~/miniconda3
wget -O ~/miniconda3/
bash ~/miniconda3/ -b -u -p ~/miniconda3
rm -rf ~/miniconda3/
~/miniconda3/bin/conda init bash
~/miniconda3/bin/conda init zsh 
then you should have the latest version of Python installed to check- write Python -V  and it should be Python 3.11.4 or above.
now run the following command 
pip install trident

after it is completed run python and inside the python environment write import trident (we are doing this to first time setup and configure trident) follow the instructions there and complete it.
now exit the python environment (Ctrl-D)
now to access the latest python in the notebook we need to make a kernel of that-
with this command it will create the kernel of the latest python - python -m ipykernel install --user
now create a new notebook and select Python 3, and now trident will work test it by import trident.

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