CmdStanPy is a lightweight interface to Stan for Python users which provides the necessary objects and functions to compile a Stan program and run Stan's samplers.

• Clean interface to Stan services so that CmdStanPy can keep up with Stan releases.

• Provides complete control - all sampler arguments have corresponding named argument for CmdStanPy sampler function.

• Easy to install,

  • minimal Python library dependencies: numpy, pandas
  • Python code doesn't interface directly with c++, only calls compiled executables

• Modular - CmdStanPy produces a sample from the posterior, downstream modules do the analysis.

CmdStan's source-code repository is hosted here on GitHub.

The CmdStanPy, CmdStan, and the core Stan C++ code are licensed under new BSD.

::

import os
from cmdstanpy import cmdstan_path, compile_model, RunSet, sample, summary

# create model
bernoulli_stan = os.path.join(cmdstan_path(), 'examples', 'bernoulli', 'bernoulli.stan')
bernoulli_model = compile_model(bernoulli_stan)

# setup data and fit the model
bernoulli_data = { "N" : 10, "y" : [0,1,0,0,0,0,0,0,0,1] }
bernoulli_fit = sample(bernoulli_model, data=bernoulli_data)

# print summary
print(summary(bern_fit))