Welcome to the forum,
Screenshots are not very useful but here is a simple example .
dat1 <- data.frame(aa = sample(1:50, 20), bb = LETTERS[1:20])
sum(dat1[1:15, "aa"])
You might find this useful: FAQ
Welcome to the forum,
Screenshots are not very useful but here is a simple example .
dat1 <- data.frame(aa = sample(1:50, 20), bb = LETTERS[1:20])
sum(dat1[1:15, "aa"])
You might find this useful: FAQ