R help - Jun 2020 - (almost) rolling or fill function?

Thanks Bert, here it is in plain.



Hello,

please see if you have a thought on how to achieve the following:

we have:

df<-data.frame(a=Sys.Date()+1:10,
? ? ? ? ? ? ? ?b=Sys.Date()+c(NA,NA,NA,rep(3,4),NA,NA,3),
? ? ? ? ? ? ? ?c=Sys.Date()+c(NA,NA,NA,rep(9,4),NA,NA,9))



the idea I have difficulty wrapping my head around is to do the following: I
need the system to look at df$a by row (lets call it the index row) and look at
df$b and df$c 1 row before the given row in df$a??(lets call it index row
-1)?and evaluate if the index row value in df$a falls into the range (>= and
<=) of the index row -1 values in df$b and df$c. If it does, then copy
over?the index row -1 values in df$b and df$c into the index row in?df$b and
df$c, if not place an NA in both cells of the?index row in?df$b and df$c.?

?examples:

1. the date value in df$a[8] is between df$b[7] and df$c[7] so we can copy the
values in?df$b[7] and df$c[7] into?df$b[8] and df$c[8]
2.??the date value in df$a[9] is between df$b[8] and df$c[8] (as we copied it in
in step 1)? so we can copy the values in?df$b[8] and df$c[8] into?df$b[9] and
df$c[9]
3.??the date value in df$a[10] is NOT between df$b[9] and df$c[9] (as we copied
it in in step 2)? so we can place NA in?df$b[10] and df$c[10]?


also would like to do this going up, too, similar to
fill(...,"downup"). On the end we would want to have this:

dfwanted<-data.frame(a=Sys.Date()+1:10,
? ? ? ? ? ? ? ?b=Sys.Date()+c(NA,NA,rep(3,7),NA),
? ? ? ? ? ? ? ?c=Sys.Date()+c(NA,NA,rep(9,7),NA))



much appreciate any help you could provide.

thanks,


Andras?


Andras?