Is there a function like rollapply for data.frame [duplicate]

Answer 1

Try this:

> library(zoo)
> DF <- data.frame(a = 1:10, b = 21:30, c = letters[1:10])
> replace(DF, 1:2, rollapply(DF[1:2], 3, sum, fill = NA))
    a  b c
1  NA NA a
2   6 66 b
3   9 69 c
4  12 72 d
5  15 75 e
6  18 78 f
7  21 81 g
8  24 84 h
9  27 87 i
10 NA NA j

Regarding the example that was added to the question after some discussion, such functionality can be layered on top of rollapply by applying it to the row indexes:

> lapply(as.data.frame(t(rollapply(1:nrow(test), 2, c))), function(ix)test[ix, ])
$V1
  Name Points
1  bob      4
2 jane      9

$V2
  Name Points
2 jane      9
3  joe      1

and here it is wrapped up a bit better:

rollapply.data.frame <- function(data, ..., fill = NULL, FUN, 
        simplify = function(x) do.call(rbind, x)) {
    fill0 <- if (!is.null(fill)) NA
    result <- lapply(
       as.data.frame(t(rollapply(1:nrow(data), ..., fill = fill0, FUN = c))), 
       function(ix) {if (all(is.na(ix))) fill else FUN(data[ix, ])}
    )
    simplify(result)
}

> rollapply(test, 2, FUN = identity, simplify = identity)
$V1
  Name Points
a  bob      4
b jane      9

$V2
  Name Points
b jane      9
c  joe      1

> rollapply(test, 2, FUN = identity, fill = NA, simplify = identity)
$V1
  Name Points
a  bob      4
b jane      9

$V2
  Name Points
b jane      9
c  joe      1

$V3
[1] NA