Hi Jeff,
Your code generated the count what I wanted.
As I emailed to Bert, yes, I made a mistake when generating the toy table, the
second count value should be 2.
Correct file is
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, 2, 2, 1, 2,
2, 2, 3, 3 ));
I also thought about removing of duplicates first and then doing a merge. For
some reason, I thought one line of code from tidyverse library could do it .
Thank You,
Ding
-----Original Message-----
From: Jeff Newmiller [mailto:jdnew...@dcn.davis.ca.us]
Sent: Friday, July 2, 2021 4:51 PM
To: Yuan Chun Ding <ycd...@coh.org>
Cc: r-help@r-project.org; r-help@r-project.org
Subject: RE: [R] add a variable a data frame to sequentially count unique rows
I am not sure I understand... you are referring to files but we are not
discussing files here. There are "input" and "output" phases yet to be dealt
with that separate the analysis you do in R from the files themselves. We are
discussing data frames here.
Regardless, you either have duplicates in your input (faulty data) or you do
not have duplicates because there are additional distinguishing columns that
you have not identified.
(https://urldefense.com/v3/__https://en.wikipedia.org/wiki/Primary_key__;!!Fou38LsQmgU!9delUPpdk-OQmYXQ0xQaFd2NDqykIVLC403VICI0m2ihoIqtK3XP0PTJ7-ev$
)
The solution to the problem that you should not have involves making a sensible
(not faulty) copy of your data, setting up the count column, and then joining
the faulty data with the sensible data.
Note that the ordering of the result happens to be retained when using
dplyr::left_join, but is not retained using most other join implementations
(such as base::merge). There can be significant performance gains to be had by
giving up on record ordering, which is one of the reasons why having a valid
primary key can be so important.
library(dplyr)
lookup_df <- ( test
%>% select( group1, group2 )
%>% filter( !duplicated( . ) )
%>% group_by( group1 )
%>% mutate( count1 = seq.int( n() ) )
%>% ungroup()
)
ans <- left_join( test, lookup_df, by = c( "group1", "group2" ) )
On Fri, 2 Jul 2021, Yuan Chun Ding wrote:
> 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))
>
>
> Ding
> -----Original Message-----
> From: Jeff Newmiller [mailto:jdnew...@dcn.davis.ca.us]
> Sent: Friday, July 2, 2021 3:36 PM
> To: r-help@r-project.org; Yuan Chun Ding <ycd...@coh.org>;
> r-help@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 <ycd...@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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> --
> Sent from my phone. Please excuse my brevity.
>
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