I have the following data frame:
df <- data.frame(A_TR1=sample(10:20, 8, replace = TRUE),A_TR2=seq(2, 16, by=2), A_TR3=seq(1, 16, by=2),
B_TR1=seq(1, 16, by=2),B_TR2=seq(2, 16, by=2), B_TR3=seq(1, 16, by=2))
> df
A_TR1 A_TR2 A_TR3 B_TR1 B_TR2 B_TR3
1 11 2 1 1 2 1
2 12 4 3 3 4 3
3 18 6 5 5 6 5
4 11 8 7 7 8 7
5 17 10 9 9 10 9
6 17 12 11 11 12 11
7 14 14 13 13 14 13
8 11 16 15 15 16 15
What I would like to do, is subtract B_TR1 from A_TR1, B_TR2 from A_TR2, and so on and create new columns from these, similar to below:
df$x_TR1 <- (df$A_TR1 - df$B_TR1)
df$x_TR2 <- (df$A_TR2 - df$B_TR2)
df$x_TR3 <- (df$A_TR3 - df$B_TR3)
> df
A_TR1 A_TR2 A_TR3 B_TR1 B_TR2 B_TR3 x_TR1 x_TR2 x_TR3
1 12 2 1 1 2 1 11 0 0
2 11 4 3 3 4 3 8 0 0
3 19 6 5 5 6 5 14 0 0
4 13 8 7 7 8 7 6 0 0
5 12 10 9 9 10 9 3 0 0
6 16 12 11 11 12 11 5 0 0
7 16 14 13 13 14 13 3 0 0
8 18 16 15 15 16 15 3 0 0
I would like to name these columns "x TR1", "x TR2", etc. I tried to do the following:
xdf <- df%>%mutate(across(starts_with("A_TR"), -across(starts_with("B_TR")), .names="x TR{.col}"))
However, I get an error in mutate():
attempt to select less than one element in integerOneIndex
I also don’t know how to create the proper column names, in terms of getting the numbers right — I am not even sure the glue() syntax allows for it. Any help appreciated here.
>Solution :
We could use .names in the first across to replace the substring ‘a’ with ‘x’ from the column names (.col) while subtracting from the second set of columns
library(dplyr)
library(stringr)
df <- df %>%
mutate(across(starts_with("A_TR"),
.names = "{str_replace(.col, 'A', 'x')}") -
across(starts_with("B_TR")))
-output
df
A_TR1 A_TR2 A_TR3 B_TR1 B_TR2 B_TR3 x_TR1 x_TR2 x_TR3
1 10 2 1 1 2 1 9 0 0
2 10 4 3 3 4 3 7 0 0
3 16 6 5 5 6 5 11 0 0
4 12 8 7 7 8 7 5 0 0
5 20 10 9 9 10 9 11 0 0
6 19 12 11 11 12 11 8 0 0
7 17 14 13 13 14 13 4 0 0
8 14 16 15 15 16 15 -1 0 0