Unexpected scenarios when using `purrr::map()` with nested lists in R
I'm maintaining legacy code that Hey everyone, I'm running into an issue that's driving me crazy. I'm working with an scenario when trying to apply a function over a nested list structure using `purrr::map()`. The structure is a list of data frames, where each data frame contains a column of numeric values. I want to calculate the mean of these numeric columns for each data frame and return a new list containing these means. However, I'm receiving an behavior that says `behavior: Argument 'x' must be of type 'list', but is of type 'double'`. Here is a simplified version of my code: ```r library(dplyr) library(purrr) # Example nested list of data frames nested_list <- list( df1 = data.frame(values = c(1, 2, 3)), df2 = data.frame(values = c(4, 5, 6)) ) # Attempt to calculate means mean_list <- map(nested_list, ~ mean(.x$values)) ``` After running the code, I get the mentioned behavior. I've verified that each element in `nested_list` is indeed a data frame, and the column `values` exists in each data frame. I tried using `map_dbl()` instead of `map()`, but the behavior remains the same. Is there a specific way to handle nested lists like this in `purrr`? What could be causing this behavior? I'm using R version 4.2.1 and the latest versions of the `dplyr` and `purrr` packages. What are your experiences with this?