How to use map2 to add column to list of dataframes

Question

I'm trying to use map2 to add a column to each dataframe within a list

Here is my attempt:

weather_data <- weather_data %>%
                map2(x, y = c("Place1", "Place2", "Place3", "Place4"), ~ x[["Area"]] = y)

The idea of this is to add a column entitled "Area" to each dataframe. So the first dataframe in the list would have a column "Area" with a value of "Place1" and so forth...

Many thanks

Answer 1

This can be achieved like so:

BTW: First. The arguments to purrr::map2 are .x and .y .

list(mtcars, iris, mtcars, iris) %>%
  purrr::map2(.y = c("Place1", "Place2", "Place3", "Place4"), function(x, y) { x[["Area"]] <- y; x })

Answer 2

We can also make use of the ~ notation in map2 along with mutate from dplyr

library(dplyr)
library(purrr)
list(mtcars, iris, mtcars, iris) %>%
    map2(c("Place1", "Place2", "Place3", "Place4"), ~ 
               .x %>%
                   mutate(Area = .y))