[R] add a variable a data frame to sequentially count unique rows

[Bert Gunter]

Your example makes no sense (to me, anyway). Please check it
carefully. Note that the count in rows 2 and 3 increment but the
counts in rows 5-7 or rows 8-9 do not. So your specification seems
inconsistent to me.

Bert Gunter

"The trouble with having an open mind is that people keep coming along
and sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )

On Fri, Jul 2, 2021 at 3:27 PM Yuan Chun Ding <ycding using coh.org> wrote:
>
> Hi R users,
>
> In this test file,
> test  <- data.frame(group1=c("g1", "g1", "g1", "g2", "g2", "g2", "g2", "g2", "g2"),
>                                        group2=c("k1", "a2", "a2", "c5", "n6", "n6", "n6", "m10","m10"),
>                                        count= c( 1,     1,    2,   1,     2,   2,     2,    3,    3 ));
>
> I have group 1 and group2 variable and want to add the count variable to sequentially count unique rows defined by group1 and group2.
>
> I hope to use the following functions in library (tidyverse),  No one worked well.
> test %>% group_by(group1, group2) %>% mutate(count = row_number())
> test %>% group_by(group1, group2) %>% mutate(count = 1:n())
> test %>% group_by(group1, group2) %>% mutate(count = seq_len(n()))
> test %>% group_by(group1, group2) %>% mutate(count = seq_along(group1, group2))
>
> Can you help me to make the third column in the test data frame?
>
> Thank you,
>
> Ding
>
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