drop_rendudant_dims() issues error with data.table

[mespe]

Summary:

When a data.table is provided as data, the internal function drop_redundant_dims() results in error.

Description:

When a data.table is provided to rstanarm as data, the following error is produced:

Called from: stop("j (the 2nd argument inside [...]) is a single symbol but column name '", 
    jsubChar, "' is not found. Perhaps you intended DT[, ..", 
    jsubChar, "]. This difference to data.frame is deliberate and explained in FAQ 1.1.")

This is because the method dispatch for [ is finding the method for data.table before data.frame.

Since the error message states this is intentional for data.tables, a check and/or coercion to data.frame might be warranted.

Reproducible Steps:

library(rstanarm)
library(data.table)
mt = as.data.table(mtcars)
stan_glm(mpg ~ cyl, data = mt)

RStanARM Version:

2.19.3

R Version:

3.6.3

Operating System:

Arch Linux 5.6.5-1

[danschrage]

I hit this same issue today, and I've submitted a pull request #434 to fix this.

I tested it on my own data and on the reproducible example above. See more detail in the PR about why it's safe to do this.