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

Jeff Newmiller jdnewm|| @end|ng |rom dcn@d@v|@@c@@u@
Sat Jul 3 00:35:49 CEST 2021

It is poor analytical design to keep duplicates. If they are not duplicates then there should be a distinguishing additional column. IMO you should re-think your analysis rather than accomplish this short-term goal only to find down the road that this duplication causes future problems.

On July 2, 2021 3:27:21 PM PDT, 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,
>Can you help me to make the third column in the test data frame?
>Thank you,
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