Extract the posterior draws of the conditional expectation. See the rstanarm package for an example.
The object to use.
Arguments passed to methods. See the methods in the rstanarm package for examples.
posterior_epred() methods should return a \(D\) by \(N\)
matrix, where \(D\) is the number of draws from the posterior distribution 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.