Add a prefix to column names

Question

When reading the following helpfile it should be possible to add a prefix to the column names :

colnames(x, do.NULL = TRUE, prefix = "col") 

The following doesn't work for me. What am I doing wrong here?

m2 <- cbind(1,1:4) colnames(m2, do.NULL = FALSE) colnames(m2) <- c("x","Y") colnames(m2) <- colnames(m2, prefix = "Sub_") colnames(m2) 

Answer 1

You have misread the help file. Here's the argument to look at:

do.NULL: logical. If FALSE and names are NULL, names are created.

Notice the and in that description. Your names are no longer NULL, so using prefix won't work.

Instead, use something like this:

> m2 <- cbind(1,1:4) > colnames(m2) <- c("x","Y") > colnames(m2) <- paste("Sub", colnames(m2), sep = "_") > m2      Sub_x Sub_Y [1,]     1     1 [2,]     1     2 [3,]     1     3 [4,]     1     4