iterors (version 1.0)

i_window: Construct a sliding window over an iterator

Description

Each element returned by i_window(obj) consists of n consecutive elements from the underlying obj, with the window advancing forward by one element each iteration.

Usage

i_window(obj, n, tail, ...)

Value

an iteror.

Arguments

obj

An iterable.

n

The width of the window to apply

tail

If a value is given, tails will be included at the beginning and end of iteration, filled with the given value.

...

passed along to iteror(object, ...)

Author

Peter Meilstrup

Examples

#' @examples
it <- i_window(iteror(letters[1:4]), 2)
nextOr(it, NA) # list("a", "b")
nextOr(it, NA) # list("b", "c")
nextOr(it, NA) # list("c", "d")

it2 <- i_window(icount(5), 2)
nextOr(it2, NA) # list(1, 2)
nextOr(it2, NA) # list(2, 3)
nextOr(it2, NA) # list(3, 4)
nextOr(it2, NA) # list(4, 5)

it <- i_window(letters[1:4], 2)
nextOr(it, NA) # list("a", "b")
nextOr(it, NA) # list("b", "c")
nextOr(it, NA) # list("c", "d")

it <- i_window(letters[1:4], 3)
nextOr(it) # list("a", "b", "c")
nextOr(it) # list("b", "c", "d")

it <- i_window(letters[1:4], 3, tail=" ")
nextOr(it) # list(" ", " ", "a")
nextOr(it) # list(" ", "a", "b")
nextOr(it) # list("a", "b", "c")
nextOr(it) # list("b", "c", "d")
nextOr(it) # list("c", "d", " ")
nextOr(it) # list("d", " ", " ")