Accessing object names and binding in R - r

Question

I like the bind_rows function in dplyr but I find it annoying that when passing the .id argument it can only add a numeric index in the new column.
I'm trying write a bind_rows_named function but am getting stuck accessing the object names. This works as expected:
bind_name_to_df <- function(df){
dfname <- deparse(substitute(df))
df %>% mutate(label=dfname)
}
a <- data_frame(stuff=1:10)
bind_name_to_df(a)
But I can't work out how to apply this to a list of data frames, e.g. using .dots. I want this to work, but I know I have the semantics for the ... wrong somehow. Can anyone shed light?
b <- data_frame(stuff=1:10)
bind_rows_named <- function(...){
return(
bind_rows(lapply(..., bind_name_to_df)))
}
bind_rows_named(a, b)

Answer 1

Here is an option using base R
bind_named <- function(...){
v1 <- sapply(match.call()[-1], deparse)
dfs <- list(...)
Map(cbind, dfs, label = v1)
}
bind_named(a, b)
#[1]]
# stuff label
#1 1 a
#2 2 a
#3 3 a
#4 4 a
#5 5 a
#6 6 a
#7 7 a
#8 8 a
#9 9 a
#10 10 a
#[[2]]
# stuff label
#1 1 b
#2 2 b
#3 3 b
#4 4 b
#5 5 b
#6 6 b
#7 7 b
#8 8 b
#9 9 b
#10 10 b
Or using tidyverse
library(tidyverse)
bind_named <- function(...) {
nm1 <- quos(...) %>%
map(quo_name)
dfs <- list(...)
dfs %>%
map2(nm1, ~mutate(., label = .y))
}
res <- bind_named(a, b)
res %>%
map(head, 2)
#[[1]]
# stuff label
#1 1 a
#2 2 a
#[[2]]
# stuff label
#1 1 b
#2 2 b
It can be also be made into a single chain
bind_named <- function(...) {
quos(...) %>%
map(quo_name) %>%
map2_df(list(...), ., ~mutate(.data = .x, label = .y))
}
bind_named(a, b)
# A tibble: 20 x 2
# stuff label
# <int> <chr>
# 1 1 a
# 2 2 a
# 3 3 a
# 4 4 a
# 5 5 a
# 6 6 a
# 7 7 a
# 8 8 a
# 9 9 a
#10 10 a
#11 1 b
#12 2 b
#13 3 b
#14 4 b
#15 5 b
#16 6 b
#17 7 b
#18 8 b
#19 9 b
#20 10 b
NOTE: Initially, we thought the OP wanted to create columns on separate datasets and get a list output. Upon clarification, the map2 is changed to map2_df which return a single dataset