Question

Which of the following finds row sums for each level of a grouping variable? (a) as.numeric(x) (b) rowsum(x, group, reorder = TRUE, …) (c) as.order(x) (d) colSums (x, na.rm = FALSE, dims = 1) The question was posed to me in examination. This is a very interesting question from Commands in portion Commands, Packages, Visualizing Data and Linear Regression of R Programming Select the correct answer from above options

Answer 1

Correct choice is (b) rowsum(x, group, reorder = TRUE, …) Explanation: rowsum compute column sums across rows of a numeric matrix-like object for each level of a grouping variable.