Determining which version of a function is active when many packages are loaded

If I have multiple packages loaded that define functions of the same name, is there an easy way to determine which version of the function is currently the active one? Like, lets say I have base R, the tidyverse, and a bunch of time series packages loaded. I'd like a function which_package("intersect") that would tell me the package name of the active version of the intersect function. I know you can go back and look at all the warning messages you recieved when installing packages, but I think that sort of manual search is not only tedious but also error-prone.

There is a function here that does sort of what I want, except it produces a table for all conflicts rather than the value for one function. I would actually be quite happy with that, and would also accept a similar function as an answer, but I have had problems with the implimentation of function given. As applied to my examples, it inserts vast amounts of white space and many duplicates of the package names (e.g. the %>% function shows up with 132 packages listed), making the output hard to read and hard to use. It seems like it should be easy to remove the white space and duplicates, and I have spent considerable time on various approaches that I expected to work but which had no impact on the outcome.

So, for an example of many conflicts:

install.packages(pkg = c("tidyverse", "fpp3", "tsbox", "rugarch", "Quandl", "DREGAR", "dynlm", "zoo", "GGally", "dyn", "ARDL", "bigtime", "BigVAR", "dLagM", "VARshrink")

lapply(x = c("tidyverse", "fable", "tsbox", "rugarch", "Quandl", "DREGAR", "dynlm", "zoo", "GGally", "dyn", "ARDL", "bigtime", "BigVAR", "dLagM", "VARshrink"), 
library, character.only = TRUE)

Solution

You can pull this information with your own function helper.

which_package <- function(fun) {
  if(is.character(fun)) fun <- getFunction(fun)
  stopifnot(is.function(fun))
  x <- environmentName(environment(fun))
  if (!is.null(x)) return(x)
}

This will return R_GlobalEnv for functions that you define in the global environment. There is also the packageName function if you really want to restrict it to packages only. For example

library(MASS)
library(dplyr)
which_package(select)
# [1] "dplyr"