use dplyr to get list items from dataframe in R - r

Question

I have a dataframe being returned from Microsoft365R:
SKA_student <- structure(list(name = "Computing SKA 2021-22.xlsx", size = 22266L,
lastModifiedBy =
structure(list(user =
structure(list(email = "my#email.com",
id = "8ae50289-d7af-4779-91dc-e4638421f422",
displayName = "Name, My"), class = "data.frame", row.names = c(NA, -1L))),
class = "data.frame", row.names = c(NA, -1L)),
fileSystemInfo = structure(list(
createdDateTime = "2021-09-08T16:03:38Z",
lastModifiedDateTime = "2021-09-16T00:09:04Z"), class = "data.frame", row.names = c(NA,-1L))), row.names = c(NA, -1L), class = "data.frame")
I can return all the lastModifiedBy data through:
SKA_student %>% select(lastModifiedBy)
lastModifiedBy.user.email lastModifiedBy.user.id lastModifiedBy.user.displayName
1 my#email.com 8ae50289-d7af-4779-91dc-e4638421f422 Name, My
But if I want a specific item in the lastModifiedBy list, it doesn't work, e.g.:
SKA_student %>% select(lastModifiedBy.user.email)
Error: Can't subset columns that don't exist.
x Column `lastModifiedBy.user.email` doesn't exist.
I can get this working through base, but would really like a dplyr answer

Answer 1

This function allows you to flatten all the list columns (I found this ages ago on SO but can't find the original post for credit)
SO_flat_cols <- function(data) {
ListCols <- sapply(data, is.list)
cbind(data[!ListCols], t(apply(data[ListCols], 1, unlist)))
}
Then you can select as you like.
SO_flat_cols (SKA_student) %>%
select(lastModifiedBy.user.email)
Alternatively you can get to the end by recursively pulling the lists
SKA_student %>%
pull(lastModifiedBy) %>%
pull(user) %>%
select(email)

Answer 2

You could use
library(dplyr)
library(tidyr)
SKA_student %>%
unnest_wider(lastModifiedBy) %>%
select(email)
This returns
# A tibble: 1 x 1
email
<chr>
1 my#email.com