to append a column to a data frame, has I use loop/if in my case?

days=Sys.Date()-1:70
price=abs(rnorm(70))
regular=rep(c(0,0,0,0,1,0,1,0,0,1),c(7,7,7,7,7,7,7,7,7,7))
y=data.frame(cbind(days,price,regular))


y is like
? ?days ? ? ?price regular
1 ?14990 0.16149463 ? ? ? 0
2 ?14989 1.69519358 ? ? ? 0
3 ?14988 1.57821998 ? ? ? 0
4 ?14987 0.47614311 ? ? ? 0
5 ?14986 0.87016180 ? ? ? 0
6 ?14985 2.55679229 ? ? ? 0
7 ?14984 0.89753533 ? ? ? 0


the output I want:
have another column appended to y, whose value is the max price in the recent 2 **regular** weeks.
So if the current row is today, then get the max price of the past 14 days (including today) if the last 2 week are regular weeks, ?if one of the last 2 weeks is not regular week, then I need to go back further to find the max price, as I need the max price for the last 2 **regular** weeks. How can I do that? Or I have to use loop/if to do it?




BTW, why the days is like 14990,14989, after cbind(days,price,regular)? before the cbind, days is like the format "2010-12-23".
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