CODEWITHSUNDEEP
rcalculated-columns
AvdH
AvdH

Reputation: 39

How to calculate a new column based on highest number in another column in R?

I have a question how to solve a problem more nicely.

I want to define a new column, based on the highest number of another column after grouping by another column. I did found a solution, see below, but I assume there are better ways to do this.

I want the totaltestno of each SN to be the highest testno of that particular SN.

Thanks for any help and suggestions!

sets <- data.frame(SN=c(1234, 1234, 2345, 3456, 7890, 7890, 7890, 1234, 1234, 2345, 3456, 7890, 7890, 7890), a= c(1,2, 3, 4, 1,2, 1,2,1,2,3,4,5,6) ,testno=
                     c(1,1,2,2,1,1,1,1,1,1,2,2,3,3))
sets

sets <- sets %>% group_by(SN) %>% 
  arrange(desc(testno), .by_group = TRUE)

setshighestno <- sets %>%  distinct(SN, .keep_all = TRUE)
setshighestno$totaltestno <- setshighestno$testno 
setshighestno$testno <- NULL 
setshighestno$a <- NULL 
setshighestno

newsets <- merge(x = sets, y=setshighestno, by = "SN")
newsets

Upvotes: 1

Views: 36

Answers (1)

akrun
akrun

Reputation: 887881

We can use

library(dplyr)
newsets %>%
    group_by(SN) %>% 
    mutate(totaltestno2 = max(testno))

Upvotes: 1

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