Shifting a column down by one

Question

Say I have a data.frame that looks like this

 df <- data.frame(AAA = rep(c(NA,sample(1:10, 1)),5),
  BBB = rep(c(NA,sample(1:10, 1)),5),
  CC         


        

Answer 1

Using dplyr

library(dplyr)
df %>%
mutate(CCC=lag(CCC)) %>%
na.omit()

Or using data.table

library(data.table)
na.omit(setDT(df)[, CCC:=c(NA, CCC[-.N])])