I have the following code that contains two vectors of different lengths, and repeats each column so that when the vectors are column bound, there is a unique combination for each row of the the new dataframe. My question is this: Is there a way to achieve the same outcome from the code below by using nested purrr::map functions?
library(tidyverse)
big <- LETTERS[1:10]
small <- letters[1:6]
ColBig <- rep(big, each =length(small))
ColSmall <- rep(small, length(big))
bind_cols(ColBig, ColSmall) %>%
setNames(c("ColBig", "ColSmall"))
CodePudding user response：
Probably something like this if you would like to use map
> do.call(rbind, map(as.list(big), ~ data.frame(ColBig = .x, ColSmall = small)))
ColBig ColSmall
1 A a
2 A b
3 A c
4 A d
5 A e
6 A f
7 B a
8 B b
9 B c
10 B d
11 B e
12 B f
13 C a
14 C b
15 C c
16 C d
17 C e
18 C f
19 D a
20 D b
21 D c
22 D d
23 D e
24 D f
25 E a
26 E b
27 E c
28 E d
29 E e
30 E f
31 F a
32 F b
33 F c
34 F d
35 F e
36 F f
37 G a
38 G b
39 G c
40 G d
41 G e
42 G f
43 H a
44 H b
45 H c
46 H d
47 H e
48 H f
49 I a
50 I b
51 I c
52 I d
53 I e
54 I f
55 J a
56 J b
57 J c
58 J d
59 J e
60 J f
but I guess expand.grid from base R should be enough
> rev(expand.grid(ColSmall = small, ColBig = big))
ColBig ColSmall
1 A a
2 A b
3 A c
4 A d
5 A e
6 A f
7 B a
8 B b
9 B c
10 B d
11 B e
12 B f
13 C a
14 C b
15 C c
16 C d
17 C e
18 C f
19 D a
20 D b
21 D c
22 D d
23 D e
24 D f
25 E a
26 E b
27 E c
28 E d
29 E e
30 E f
31 F a
32 F b
33 F c
34 F d
35 F e
36 F f
37 G a
38 G b
39 G c
40 G d
41 G e
42 G f
43 H a
44 H b
45 H c
46 H d
47 H e
48 H f
49 I a
50 I b
51 I c
52 I d
53 I e
54 I f
55 J a
56 J b
57 J c
58 J d
59 J e
60 J f
CodePudding user response：
You can try:
map_df(big, ~map(small, ~c(ColBig = .y, ColSmall = .x), .y = .x))
# # A tibble: 60 x 2
# ColBig ColSmall
# <chr> <chr>
# 1 A a
# 2 A b
# 3 A c