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

Yuan Chun Ding ycd|ng @end|ng |rom coh@org
Sat Jul 3 00:42:21 CEST 2021

Hi Jeff,

Thank you for your quick response!!
I made this following summary file, however, I want to add the count number sequentially into the original file, because I have several more columns to explain or annotate the first two columns.

count_test <- test %>% group_by(group1 ) %>%summarise(Number_of_region = n_distinct(group2))

-----Original Message-----
From: Jeff Newmiller [mailto:jdnewmil using dcn.davis.ca.us] 
Sent: Friday, July 2, 2021 3:36 PM
To: r-help using r-project.org; Yuan Chun Ding <ycding using coh.org>; r-help using r-project.org
Subject: Re: [R] add a variable a data frame to sequentially count unique rows

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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Sent from my phone. Please excuse my brevity.

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