Group input by rows
rowwise is used for the results of
do when you
create list-variables. It is also useful to support arbitrary
complex operations that need to be applied to each row.
Input data frame.
rowwise grouping only works with data frames. Its
main impact is to allow you to work with list-variables in
mutate without having to
[]. This makes
summarise() on a rowwise tbl
effectively equivalent to plyr's
df <- expand.grid(x = 1:3, y = 3:1) df %>% rowwise() %>% do(i = seq(.$x, .$y)) .Last.value %>% summarise(n = length(i))