Updated docs about icount's stop argument. #39

Author: ramhiser

NEWS

@@ -1,3 +1,10 @@
+# itertools 0.1.3
+
+## Miscellaneous
+
+* `icount()` now has an optional `stop` argument. By default, the sequence is
+  neverending.
+
 # itertools 0.1.2
 
 ## Iterators

R/icount.r

@@ -1,7 +1,9 @@
-#' Iterator of neverending numeric sequence with initial value and step size
+#' Iterator of numeric sequence with initial value and step size
 #'
-#' Constructs an iterator that generates a neverending sequence of evenly spaced
-#' values starting with \code{icount}. The step size is given by \code{step}.
+#' Constructs an iterator that generates a sequence of evenly spaced values
+#' starting with \code{icount}. The step size is given by \code{step}. By
+#' default, the sequence is neverending unless the optional \code{stop} is
+#' provided.
 #'
 #' NOTE: Use a negative \code{step} size to generate decreasing sequences.
 #'
@@ -11,6 +13,7 @@
 #' @export
 #' @param start sequence's initial value
 #' @param step sequence's step size
+#' @param stop optional stopping point to sequence
 #' @return sequence's iterator
 #'
 #' @examples
@@ -23,12 +26,15 @@
 #' iterators::nextElem(it2)
 #' iterators::nextElem(it2)
 #' iterators::nextElem(it2)
+#'
+#' it3 <- icount(start=1, stop=3)
+#' iterators::nextElem(it3)
+#' iterators::nextElem(it3)
+#' iterators::nextElem(it3)
+#'
 icount <- function(start=0, step=1, stop=NULL) {
   start <- as.numeric(start)
   step <- as.numeric(step)
-  if (!is.null(stop)) {
-    stop <- as.numeric(stop)
-  }
 
   if (length(start) != 1) {
     stop("'start' must be a numeric value of length 1")
@@ -37,6 +43,13 @@ icount <- function(start=0, step=1, stop=NULL) {
     stop("'step' must be a numeric value of length 1")
   }
 
+  if (!is.null(stop)) {
+    stop <- as.numeric(stop)
+    if (length(stop) != 1) {
+      stop("'stop' must be a numeric value of length 1")
+    }
+  }
+
   current_val <- start - step
   nextElem <- function() {
     current_val <<- current_val + step

man/icount.Rd

@@ -2,21 +2,25 @@
 % Please edit documentation in R/icount.r
 \name{icount}
 \alias{icount}
-\title{Iterator of neverending numeric sequence with initial value and step size}
+\title{Iterator of numeric sequence with initial value and step size}
 \usage{
 icount(start = 0, step = 1, stop = NULL)
 }
 \arguments{
 \item{start}{sequence's initial value}
 
 \item{step}{sequence's step size}
+
+\item{stop}{optional stopping point to sequence}
 }
 \value{
 sequence's iterator
 }
 \description{
-Constructs an iterator that generates a neverending sequence of evenly spaced
-values starting with \code{icount}. The step size is given by \code{step}.
+Constructs an iterator that generates a sequence of evenly spaced values
+starting with \code{icount}. The step size is given by \code{step}. By
+default, the sequence is neverending unless the optional \code{stop} is
+provided.
 }
 \details{
 NOTE: Use a negative \code{step} size to generate decreasing sequences.
@@ -34,5 +38,10 @@ it2 <- icount(start=5.5, step=1.5)
 iterators::nextElem(it2)
 iterators::nextElem(it2)
 iterators::nextElem(it2)
+
+it3 <- icount(start=1, stop=3)
+iterators::nextElem(it3)
+iterators::nextElem(it3)
+iterators::nextElem(it3)
 }