r - dplyr Update a cell in a data.frame -

df <-data.frame(x=c(1:5),y=c(letters[1:5]))

let's want modify last row,

update.row<-filter(df,x==5) %>% mutate(y="r")

how update row data.frame ? way, found albeit strange way anti-join , append results.

df <-anti_join(df,update.row,by="x") %>%      bind_rows(update.row)

however, seems inelegant way achieve simple task. ideas appreciated...

with data.table, can assign (:=) value rows i true. efficient assignment done in place.

library(data.table) setdt(df)[x==5, y:="r"] df #   x y #1: 1 #2: 2 b #3: 3 c #4: 4 d #5: 5 r

as op mentioned last row, more general way is

setdt(df)[.n, y:= "r"]

or @thelatemail mentioned, if want replace row mention row index in i i.e. in case 5.

setdt(df)[5, y:="r"]

Camp