I have this example list that contains 3 dataframes:
library(tidyverse)
list_df <- iris %>%
group_by(Species) %>%
slice(1:3) %>%
ungroup() %>%
group_split(Species)
I want to add a new row at the end of each dataframe that shows the column median
My try so far (and earlier this day I am sure it worked) is not working:
list_df %>%
map_dfr([,1:4], ~ .x %>%
add_row(!!!map(., median)))
I want to learn why my code is not working and what exactly !!! is for ins this situation.
The [, 1:4] doesn't include the data i.e. it only shows the index and thus it fails
list_df %>%
map_dfr(~ .x %>%
add_row(!!! map(.[1:4], median)))
-output
# A tibble: 12 x 5
Sepal.Length Sepal.Width Petal.Length Petal.Width Species
<dbl> <dbl> <dbl> <dbl> <fct>
1 5.1 3.5 1.4 0.2 setosa
2 4.9 3 1.4 0.2 setosa
3 4.7 3.2 1.3 0.2 setosa
4 4.9 3.2 1.4 0.2 <NA>
5 7 3.2 4.7 1.4 versicolor
6 6.4 3.2 4.5 1.5 versicolor
7 6.9 3.1 4.9 1.5 versicolor
8 6.9 3.2 4.7 1.5 <NA>
9 6.3 3.3 6 2.5 virginica
10 5.8 2.7 5.1 1.9 virginica
11 7.1 3 5.9 2.1 virginica
12 6.3 3 5.9 2.1 <NA>
If we want to add a row with the group information, another option is group_modify (without splitting)
iris %>%
group_by(Species) %>%
slice(1:3) %>%
group_modify(~ .x %>%
add_row(!!! map(.x, median))) %>%
ungroup
-output
# A tibble: 12 x 5
Species Sepal.Length Sepal.Width Petal.Length Petal.Width
<fct> <dbl> <dbl> <dbl> <dbl>
1 setosa 5.1 3.5 1.4 0.2
2 setosa 4.9 3 1.4 0.2
3 setosa 4.7 3.2 1.3 0.2
4 setosa 4.9 3.2 1.4 0.2
5 versicolor 7 3.2 4.7 1.4
6 versicolor 6.4 3.2 4.5 1.5
7 versicolor 6.9 3.1 4.9 1.5
8 versicolor 6.9 3.2 4.7 1.5
9 virginica 6.3 3.3 6 2.5
10 virginica 5.8 2.7 5.1 1.9
11 virginica 7.1 3 5.9 2.1
12 virginica 6.3 3 5.9 2.1
If we want to add the median rows,
iris %>%
group_by(Species) %>%
slice(1:3) %>%
group_modify(~ .x %>%
add_row(!!! map(.x, median))) %>%
mutate(rn = row_number()) %>%
ungroup %>%
summarise(across(2:5, ~ c(.[rn < max(rn)],
sum(.[rn == max(rn)]))), Species = c(Species[rn != max(rn)],
"Total"))
-output
# A tibble: 10 x 5
Sepal.Length Sepal.Width Petal.Length Petal.Width Species
<dbl> <dbl> <dbl> <dbl> <chr>
1 5.1 3.5 1.4 0.2 1
2 4.9 3 1.4 0.2 1
3 4.7 3.2 1.3 0.2 1
4 7 3.2 4.7 1.4 2
5 6.4 3.2 4.5 1.5 2
6 6.9 3.1 4.9 1.5 2
7 6.3 3.3 6 2.5 3
8 5.8 2.7 5.1 1.9 3
9 7.1 3 5.9 2.1 3
10 18.1 9.4 12 3.8 Total