phpstats / cmdstanphp

v0.1.2 2026-10-31 15:26 UTC

Requires

• php: >=8.2 <8.6
• ext-json: *

Requires (Dev)

• phpunit/phpunit: ^11.5
• squizlabs/php_codesniffer: ^3.13

Suggests

• ext-ffi: Required for model methods (log_prob, gradients, constrain/unconstrain) and expose_functions()
• ext-phit: Required for loo(moment_match: true): provides the Phit\draws_moments, Phit\draws_covariance_map, and Phit\draws_affine kernels; StanData::fromFormula() also needs its Phit\model_matrix()
• phpstats/phibble: Data frames: pass a Phibble\DataFrame as model data, and get draws and summaries back with drawsTable() and summaryTable() (phibble requires PHP 8.3 or later)

MIT

Published on Packagist.org on 2026-10-31 17:02 UTC

README

CmdStanPHP fits Stan models from PHP through CmdStan. It is a port of CmdStanR 1.0 and keeps CmdStanR's function and option names. It compiles Stan programs, runs MCMC, optimization, Laplace, ADVI, Pathfinder, and standalone generated quantities, and returns draws, summaries, diagnostics, PSIS-LOO, and WAIC as PHP arrays. No R installation is needed.

Documentation: https://cmdstanphp.phpstats.org/docs

Installation

composer require phpstats/cmdstanphp

Requirements:

• PHP 8.2, 8.3, 8.4, or 8.5
• The JSON extension
• PHP's proc_open() function
• CmdStan 2.37 or later
• make and a C++ compiler that CmdStan supports

CmdStanPHP finds CmdStan through the CMDSTAN environment variable or under ~/.cmdstan. CmdStan\install_cmdstan('2.40.0', cores: 2) downloads and builds an official release. The installation guide covers the toolchain, the supported platforms, and the optional FFI extension, phit extension, phibble package, and vl-convert binary.

Example

bernoulli.stan:

data {
  int<lower=0> N;
  array[N] int<lower=0, upper=1> y;
}
parameters {
  real<lower=0, upper=1> theta;
}
model {
  theta ~ beta(1, 1);
  y ~ bernoulli(theta);
}

bernoulli.php, in the same directory:

<?php
require __DIR__.'/vendor/autoload.php';

use function CmdStan\cmdstan_model;

$model = cmdstan_model(__DIR__.'/bernoulli.stan');

$fit = $model->sample(
    data: ['N' => 10, 'y' => [0, 1, 0, 0, 0, 0, 0, 0, 0, 1]],
    seed: 123,
    chains: 4,
    parallel_chains: 4,
    show_messages: false,
);

print_r($fit->summary('theta'));
print_r($fit->diagnosticSummary());

Getting started shows and explains the output.

Compatibility

CmdStanPHP does not implement every CmdStanR feature. The compatibility page maps CmdStanR's names to CmdStanPHP's and lists the differences and the missing features. Verification describes the tests, including the comparisons with CmdStanR, posterior, loo, and bayesplot.

Development

composer install
composer test                 # unit tests, no CmdStan needed
composer test:integration     # compiles and runs real models
composer test:compatibility   # compares with R; needs CmdStanR and R packages
composer lint

See Contributing.

License

MIT. The example models in resources/examples/ come from CmdStanR under its BSD 3-Clause license (see the NOTICE there). CmdStan and CmdStanR are separate Stan projects. CmdStanPHP is an independent implementation and not an official Stan interface.