R Reorder matrix columns by matching colnames to list of string

Question

Sorry if this is very basic. I have a list of names and a matrix with those names as column names. However, the colnames are in a different order.

Eg. List of name

Answer 1

You just have to use a vector for the names and the [-operator as follows:

col.order <- c("colname4","colname3","colname2","colname5","colname1")
M[,col.order]