Of course this is a cosmetic issue...
wait <- function(i) Sys.sleep(0.3*rexp(1))
ldply(1:20, wait, .progress="text", .parallel = TRUE)
# |========== | 15%
#data frame with 0 columns and 0 rows
# by the wait l_ply does not accept .parallel argument:
l_ply(1:20, wait, .progress="text", .parallel = TRUE)
#| | 0%Error in .fun(.data[[i]], ...) : unused argument(s) (.parallel = TRUE)
Yes, it's unfortunately progress bars + parallel computation is very difficult.