Question

For example, I have a matrix k

> k
  d e
a 1 3
b 2 4

I want to apply a function on k

> apply(k,MARGIN=1,function(p) {p+1})
a b
d 2 3
e 4 5

However, I also want to print the rowname of the row being apply so that I can know which row the function is applied on at that time.

It may looks like this:

apply(k,MARGIN=1,function(p) {print(rowname(p)); p+1})

But I really don’t do how to do that in R.
Does anyone has any idea?

Answer 1

As far as I know you cannot do that with apply, but you could loop through the rownames of your data frame. Lame example:

lapply(rownames(mtcars), function(x) sprintf('The mpg of %s is %s.', x, mtcars[x, 1]))