Cannot run exmaple python code about bridgestan

[WardBrian]

This error sounds like Python is preferring to load the folder called bridgestan over the Python module. The easiest thing to do is probably to re-name the downloaded bridgestan to something like bridgestan_repo and then pip install bridgestan_repo/python

[fredhu0514]

Hi, I updated the module import, but it shows a new error.

import bridgestan.python.bridgestan as bs
import numpy as np

stan = "../test_models/bernoulli/bernoulli.stan"
data = "../test_models/bernoulli/bernoulli.data.json"
model = bs.StanModel.from_stan_file(stan, data)

print(f"This model's name is {model.name()}.")
print(f"It has {model.param_num()} parameters.")

x = np.random.random(model.param_unc_num())
q = np.log(x / (1 - x))  # unconstrained scale
lp, grad = model.log_density_gradient(q, jacobian=False)
print(f"log_density and gradient of Bernoulli model: {(lp, grad)}")

Error msg:

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
[<ipython-input-22-fb3d9974c29f>](https://localhost:8080/#) in <module>
      4 stan = "../test_models/bernoulli/bernoulli.stan"
      5 data = "../test_models/bernoulli/bernoulli.data.json"
----> 6 model = bs.StanModel.from_stan_file(stan, data)
      7 
      8 print(f"This model's name is {model.name()}.")

[/content/bridgestan/python/bridgestan/model.py](https://localhost:8080/#) in from_stan_file(cls, stan_file, model_data, stanc_args, make_args, seed, chain_id)
    196         :raises RuntimeError: If compilation fails.
    197         """
--> 198         result = compile_model(stan_file, stanc_args=stanc_args, make_args=make_args)
    199         return cls(str(result), model_data, seed=seed, chain_id=chain_id)
    200 

[/content/bridgestan/python/bridgestan/compile.py](https://localhost:8080/#) in compile_model(stan_file, stanc_args, make_args)
     84 
     85     stanc_args
---> 86     output = generate_so_name(file_path)
     87     cmd = (
     88         [MAKE]

[/content/bridgestan/python/bridgestan/compile.py](https://localhost:8080/#) in generate_so_name(model)
     51 def generate_so_name(model: Path):
     52     name = model.stem
---> 53     return model.with_stem(f"{name}_model").with_suffix(".so")
     54 
     55 

AttributeError: 'PosixPath' object has no attribute 'with_stem'

[WardBrian]

That seems like you’re using a version of python earlier than 3.9, which is the minimum version we support. It’s possible changing that one thing is all you’d need to use an older version, but there could be more places we use 3.9 specific code

[fredhu0514]

The error actually happened in Python 3.9.16. Here is the google colab file I'm running. Even in Python 3.9.16, the posix error keeps showing.

[WardBrian]

I ran your file and confirmed the output. But, I then added this cell:

import sys
sys.version

3.8.10 (default, Nov 14 2022, 12:59:47) \n[GCC 9.4.0]

The google collab kernel you are using seems to be detached from the python command in the collab workspace.

[fredhu0514]

Interesting, thx!