map over list, get item name and content

user_1024586 0
Viewed 49
my_dfs <- list(
  mtcars = mtcars,
  diamonds = diamonds
)
map(.x = my_dfs, ~ print(.x %>% str)) # OK

But if I also want to access the name of the item in the list being printed, how can I do that?

map(.x = my_dfs, ~ print(.id)) # found a reference to .id in the docs.
Error in print(.id) : object '.id' not found

Better yet, I would like both in one call to map, e.g.

map(.x = my_dfs, ~ print('About to print str of ' [somehow get list item name here] .x %>% str))
purrr r
2 Answers

Use imap(). The contents will be referenced by .x, the name by .y.

z <- list(x = "whats in x",
          y = "whats in y")

imap(z, ~ paste(.y, "has contents:", .x))
# $x
# [1] "x has contents: whats in x"
# 
# $y
# [1] "y has contents: whats in y"
user_109174790

In base R, this can be done with Map

Map(function(x, y) paste(y, "has contents:", x), z, names(z))
#$x
#[1] "x has contents: whats in x"

#$y
#[1] "y has contents: whats in y"
user_37322710
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