Sum of columns into a new column

mat1 <- matrix(1:20, ncol = 4)
This just creates a matrix as sample data. I created a matrix of the numbers from 1 to 20 arranged in 4 rows. The ncol specifies the number of rows.
.

``````mat1
[,1] [,2] [,3] [,4]
[1,]    1    6   11   16
[2,]    2    7   12   17
[3,]    3    8   13   18
[4,]    4    9   14   19
[5,]    5   10   15   20
``````

It would help to have some data---see the FAQ posted below but if I understand you properly you just need to do:

``````rs  <-  rowSums(mydata[ , 6:44])
``````

and then do a cbind().

Here is a toy example with "dat1" as a dataframe.

``````dat1  <-  structure(list(rr = c("a", "b", "c", "d", "e"), X1 = 1:5, X2 = 6:10,
X3 = 11:15, X4 = 16:20), class = "data.frame", row.names = c(NA,
-5L))

rs  <-  rowSums(dat1[ , 2 : 5])

dat2  <-  cbind(dat1, rs)
``````

I do not usually use tidyverse so I don"t know if mutate() is the correct approach. My approach is simple basic R which will do the job. Note, if you have NAs in the data you will need to use

``````rowSums(mydata[ , 6:44], na.rm = TRUE)

``````