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

Here is how you should be creating your dataframe so that each element
has the proper mode:
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))
str(y)
'data.frame':   70 obs. of  3 variables:
 $ days   : num  14991 14990 14989 14988 14987 ... # notice is it numeric
 $ price  : num  0.626 0.184 0.836 1.595 0.33 ...
 $ regular: num  0 0 0 0 0 0 0 0 0 0 ...
y <- data.frame(days, price, regular)
str(y)
'data.frame':   70 obs. of  3 variables:
 $ days   :Class 'Date'  num [1:70] 14991 14990 14989 14988 14987 ...#
here it is 'Date'
 $ price  : num  0.626 0.184 0.836 1.595 0.33 ...
 $ regular: num  0 0 0 0 0 0 0 0 0 0 ...
y
days      price regular
1  2011-01-17 0.62645381       0
2  2011-01-16 0.18364332       0
3  2011-01-15 0.83562861       0
4  2011-01-14 1.59528080       0
5  2011-01-13 0.32950777       0
6  2011-01-12 0.82046838       0
7  2011-01-11 0.48742905       0
8  2011-01-10 0.73832471       0
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".
? ? ? ?[[alternative HTML version deleted]]

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Jim Holtman
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What is the problem that you are trying to solve?

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

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