Handling complex nested lists in R while extracting specific elements
I'm following best practices but I've been struggling with this for a few days now and could really use some help... I've been struggling with this for a few days now and could really use some help. I'm currently working with a nested list structure in R that contains various data frames, and I'm struggling to extract specific elements from it. Here's a simplified version of the structure I'm dealing with: ```r nested_list <- list( df1 = data.frame(a = 1:3, b = c('x', 'y', 'z')), df2 = data.frame(a = 4:6, b = c('u', 'v', 'w')), group = list( df3 = data.frame(a = 7:9, b = c('p', 'q', 'r')), df4 = data.frame(a = 10:12, b = c('m', 'n', 'o')) ) ) ``` I want to extract the second column (`b`) from each data frame, including those within the nested `group`. I've tried using `lapply()` to loop through the list, but I'm running into issues accessing the nested data frames correctly. Here’s what I attempted: ```r result <- lapply(nested_list, function(x) { if (is.data.frame(x)) { return(x$b) } }) ``` This returns a list with `NULL` values for the nested data frames. I also tried using `purrr::map()` but faced a similar question. The behavior I receive is: `behavior in x$b : $ operator is invalid for atomic vectors` when trying to access `x$b` for the nested data frames. What’s the best way to handle this situation? I need a flat vector containing all `b` values, regardless of the nesting level. Any insights would be greatly appreciated! I'm working on a web app that needs to handle this. How would you solve this? Any ideas what could be causing this? The project is a REST API built with R.