How to remove duplicated column names in R?

Question

I have very big matrix, I know that some of the colnames of them are duplicated. so I just want to find those duplicated colnames and remove on of the column from duplicate. I tried duplicate(), but it removes the duplicate entries. Would someone help me to implment this in R ? the point is that, duplicate colnames, might not have duplicate entires.

Answer 1

Let's say temp is your matrix

temp <- matrix(seq_len(15), 5, 3) colnames(temp) <- c("A", "A", "B")  ##      A  A  B ## [1,] 1  6 11 ## [2,] 2  7 12 ## [3,] 3  8 13 ## [4,] 4  9 14 ## [5,] 5 10 15 

You could do

temp <- temp[, !duplicated(colnames(temp))]  ##      A  B ## [1,] 1 11 ## [2,] 2 12 ## [3,] 3 13 ## [4,] 4 14 ## [5,] 5 15 

Or, if you want to keep the last duplicated column, you can do

temp <- temp[, !duplicated(colnames(temp), fromLast = TRUE)]   ##       A  B ## [1,]  6 11 ## [2,]  7 12 ## [3,]  8 13 ## [4,]  9 14 ## [5,] 10 15 

Answer 2

Or assuming data.frames you could use subset:

subset(iris, select=which(!duplicated(names(.))))  

Note that dplyr::select is not applicable here because it requires column-uniqueness in the input data already.