man/icanhasnext.Rd man/liply.Rd @@ -14,6 +14,7 @@ Description: plyr is a set of tools that solves a common set of URL: http://had.co.nz/plyr Depends: R (>= 2.8) Suggests: RUnit, abind, tcltk +Enhances: iterator License: GPL LazyData: true Collate: 'dimensions.r' 'helper-arrange.r' 'helper-col-wise.r' DESCRIPTION @@ -1,10 +1,11 @@ #' An indexed array -#' Create a indexed array, a space efficient way of indexing into a large array +#' Create a indexed array, a space efficient way of indexing into a large +#' array. #' #' @param env environment containing data frame #' @param index list of indices #' @keywords internal -#' @aliases indexex_array [[.indexed_array names.indexed_array +#' @aliases indexed_array [[.indexed_array names.indexed_array #' length.indexed_array indexed_array <- function(env, index) { exact <- all(laply(index, is.numeric)) R/indexed-array.r @@ -1,3 +1,19 @@ +#' Add has next functionality to any iterator +#' +#' The iterator package relies of catching \code{StopIteration} errors +#' to detect when iteration is complete. This function wraps any interator +#' with an iterator that additionally provides a boolean \code{hasNext} method +#' which reports whether or not the iterator has another element. This +#' simplifies programming as you can use a simple while loop, instead of +#' needing a \code{tryCatch} to detect completion. +#' +#' @keywords internal +#' @aliases end_iteration iteration_has_ended new_iterator is.iterator +#' icanhasnext +#' @param iterator iterator to add \code{hasNext} capability to +#' @examples +#' it <- icanhasnext(icount(3)) +#' while(it$hasNext()) print(it$nextElem()) icanhasnext <- function(iterator) { # If already has hasNext function return iterator unchanged if (!is.null(iterator$hasNext)) return(iterator) @@ -33,6 +49,7 @@ icanhasnext <- function(iterator) { new_iterator(nextElem, hasNext = hasNext) } + end_iteration <- function() stop('StopIteration', call.=FALSE) iteration_has_ended <- function(e) { identical(conditionMessage(e), 'StopIteration') R/iterator.r @@ -1,3 +1,15 @@ +#' Experimental iterator based version of llply. +#' +#' Because iterators do not have known length, \code{liply} starts by +#' allocating an output list of length 50, and then doubles that length +#' whenever it runs out of space. This gives O(n ln n) performance rather +#' than the O(n ^ 2) performance from the naive strategy of growing the list +#' each time. +#' +#' @keywords manip +#' @param .iterator iterator object +#' @param .fun function to apply to each piece +#' @param ... other arguments passed on to \code{.fun} liply <- function(.iterator, .fun = NULL, ...) { stopifnot(is.iterator(.iterator)) if (is.null(.fun)) return(as.list(.iterator)) R/ply-iterator.r @@ -2,9 +2,10 @@ \title{An indexed array...} \usage{indexed_array(env, index)} \description{An indexed array -Create a indexed array, a space efficient way of indexing into a large array} +Create a indexed array, a space efficient way of indexing into a large +array.} \keyword{internal} -\alias{indexex_array} +\alias{indexed_array} \alias{[[.indexed_array} \alias{names.indexed_array} \alias{length.indexed_array} man/indexed_array.Rd 520fc56f56b5db25dbe0548f65e8510c185a5972 hadley h.wickham@gmail.com http://github.com/hadley/plyr/commit/f4d6c9fff31c08528df2b9456db88a992c2870c6 f4d6c9fff31c08528df2b9456db88a992c2870c6 2009-09-15T06:59:46-07:00 2009-09-15T06:59:46-07:00 Complete documentation e96fba9418b6a51bd3ccf3ffc2f08ec957d50a18 hadley h.wickham@gmail.com