creating week from date

gistfile1.txt

> df <- data.frame(date = c('2017-10-01', '2017-10-11'))
> df$date <- as.Date(df$date)
> df
        date
1 2017-10-01
2 2017-10-11
> sapply(df$date, function(d) {if (d < as.Date('2017-10-07')) 1 else 0})
[1] 1 0
> df$week1 <- sapply(df$date, function(d) {if (d < as.Date('2017-10-07')) 1 else 0})
> df
        date week1
1 2017-10-01     1
2 2017-10-11     0
>