prior_summary() |> dplyr::select() alters the content in the prior column #1761
Description
It looks like there's a bug when you try to subset the columns from prior_summary() with dplyr::select(). Some of the information in the prior column changes. To give a sense, here's a simplified version of fit2 from the inhaler documentation.
# Load
library(tidyverse)
library(brms)
# Fit
fit2.1 <- brm(rating ~ treat + (1 | subject),
data = inhaler,
family = cumulative(),
prior = set_prior("normal(0, 5)"),
cores = 4, seed = 1)
# Before `select()`
prior_summary(fit2.1)
prior class coef group resp dpar nlpar lb ub source
normal(0,5) b user
normal(0,5) b treat (vectorized)
student_t(3, 0, 2.5) Intercept default
student_t(3, 0, 2.5) Intercept 1 (vectorized)
student_t(3, 0, 2.5) Intercept 2 (vectorized)
student_t(3, 0, 2.5) Intercept 3 (vectorized)
student_t(3, 0, 2.5) sd 0 default
student_t(3, 0, 2.5) sd subject 0 (vectorized)
student_t(3, 0, 2.5) sd Intercept subject 0 (vectorized)
To my eye, this all looks correct. Now see what happens when we use select().
prior_summary(fit2.1) |>
select(prior, class, coef, group)
prior class coef group source
normal(0,5) b (unknown)
(flat) b treat (unknown)
student_t(3, 0, 2.5) Intercept (unknown)
(flat) Intercept 1 (unknown)
(flat) Intercept 2 (unknown)
(flat) Intercept 3 (unknown)
student_t(3, 0, 2.5) sd (unknown)
(flat) sd subject (unknown)
(flat) sd Intercept subject (unknown)
Several rows have now changed to (flat) in the prior column. The issue appears the same if you instead use the get_prior(fit2.1) or fit2.1$prior methods. It also persists if you use the base bracket notation in place of select() (prior_summary(fit2.1)[, 1:4]).
Though my primary interest is with the prior column, I find the behavior of the source column surprising, too. When I tried to drop that column with select(), it still appeared in the print output, but now with all (unknown).