We define a new function log_lik() rather than a
stats::logLik() method because (in addition to the conceptual
difference) the documentation for logLik() states that the return value
will be a single number, whereas log_lik() returns a matrix. See
the log_lik.stanreg()
method in the rstanarm package for an example of defining a method.
log_lik(object, ...)The object to use.
Arguments passed to methods. See the methods in the rstanarm package for examples.
log_lik() methods should return a \(S\) by \(N\) matrix,
where \(S\) is the size of the posterior sample (the number of draws from
the posterior distribution) and \(N\) is the number of data points.
The rstanarm package (mc-stan.org/rstanarm) for example methods (CRAN, GitHub).
Guidelines and recommendations for developers of R packages interfacing with Stan and a demonstration getting a simple package working can be found in the vignettes included with rstantools and at mc-stan.org/rstantools/articles.
# See help("log_lik", package = "rstanarm")