library(tidyverse)
data6 <- data.frame(store =c(rep(1,6),rep(2,6)),
week =rep(c(1,2),6),
year= rep(c(rep(2017,2),rep(2018,2),rep(2019,2)),2))
data6 %>% mutate(ynum=2*(year-2017),
week2 = week+ynum)
# store week year ynum week2
# 1 1 1 2017 0 1
# 2 1 2 2017 0 2
# 3 1 1 2018 2 3
# 4 1 2 2018 2 4
# 5 1 1 2019 4 5
# 6 1 2 2019 4 6
# 7 2 1 2017 0 1
# 8 2 2 2017 0 2
# 9 2 1 2018 2 3
# 10 2 2 2018 2 4
# 11 2 1 2019 4 5
# 12 2 2 2019 4 6