apply over matrix by column - any way to get column name?

Question

I\'m calling apply(data, 2, function(x) {...}) where data is a matrix. Is there any way for the function to know the name of the column whose valu

Answer 1

You can use sapply on colnames(data):

set.seed(21)
Data <- matrix(rnorm(10),5,2)
colnames(Data) <- c("one","two")
sapply(colnames(Data), function(x) sum(Data[,x]))
#       one       two 
#  3.987540 -2.010875 
colSums(Data)
#       one       two 
#  3.987540 -2.010875