I have dataset with day, month and year. I need to use week.
How can I converte day, month, year into week in R?
I am assuming you need the week of the year.
If the values are in a POSIX object you can use strftime() function for C like conversions, e.g., strftime(d, "%W").
or more generally you can use the format() function, e.g., format(d, "%W").