Iterator: Iterator

Description

An Iterator is an object that allows to iterate over sequences. It implements _next and get to iterate and retrieve the value of the sequence it is associated with.

Usage

Iterator
iter(x)
is.iterator(x)
itbegin(it)
itget(it)
itget_next(it)
itpos(it)
ithas_next(it)
itnext(it)

Arguments

iterable object, e.g., list, vector, Container

Iterator object

Format

An object of class R6ClassGenerator of length 24.

Constructor

Iterator$new(x)

Iterator interface

begin(): Reset iterator position to 1.
get(): Get value at current iterator position.
get_next(): Get value after incrementing by one.
pos(): Return current iterator position.
has_next(): Return TRUE if there is a next element.
next(): Increment iterator to point at next element.

S3 method interface

itbegin(it): Reset iterator position to 1.
itget(it): Get value at current iterator position.
itget_next(): Get value after incrementing by one.
itpos(): Return current iterator position.
ithas_next(it): Return TRUE if there is a next element.
itnext(it): Increment iterator to point at next element.

Examples

Run this code

# NOT RUN {
# Iterator on primitive list
it <- Iterator$new(list("A", 1, 2))
while(it$has_next()) {
print(it$get_next())
}
it$has_next()   # FALSE
print(it)       # <Iterator> at position 3
it$begin()
print(it)       # <Iterator> at position 0

# Iterator from Container object
d <- deque(1:3)
it <- iter(d)
sum <- 0
while(it$has_next()) {
sum <- sum + it$get_next()
}
print(sum)

# S3 method interface
it <- iter(list("A", 1, 2))
while(ithas_next(it)) {
print(itget_next(it))
}
ithas_next(it)   # FALSE
print(it)       # <Iterator> at position 3
itbegin(it)
print(it)       # <Iterator> at position 0
# }

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