[R-gregmisc-commits] r2073 - in pkg/gdata: R man

[noreply at r-forge.r-project.org]

Author: warnes
Date: 2016-02-03 21:13:49 +0100 (Wed, 03 Feb 2016)
New Revision: 2073

Modified:
   pkg/gdata/R/first.R
   pkg/gdata/man/first.Rd
Log:
Add assignment versions of first() and last()

Modified: pkg/gdata/R/first.R
===================================================================
--- pkg/gdata/R/first.R	2016-02-03 20:00:57 UTC (rev 2072)
+++ pkg/gdata/R/first.R	2016-02-03 20:13:49 UTC (rev 2073)
@@ -1,3 +1,16 @@
 # Simply call 'first' or 'last' with a different default value for 'n'.
 first <- function(x, n=1, ...) head(x, n=n, ...)
 last  <- function(x, n=1, ...) tail(x, n=n, ...)
+
+"first<-" <- function(x, n=1, ..., value )
+{
+  x[1:n] <- value[1:n]
+  x
+}
+
+"last<-" <- function(x, n=1, ..., value )
+{
+  index <- seq( length(x)-n+1, length(x) )
+  x[index] <- value[1:n]
+  x
+}

Modified: pkg/gdata/man/first.Rd
===================================================================
--- pkg/gdata/man/first.Rd	2016-02-03 20:00:57 UTC (rev 2072)
+++ pkg/gdata/man/first.Rd	2016-02-03 20:13:49 UTC (rev 2073)
@@ -1,6 +1,8 @@
 \name{first}
 \alias{first}
 \alias{last}
+\alias{first<-}
+\alias{last<-}
 \title{Return first or last element of an object}
 \description{
   Return first or last element of an object.  These functions are convenience
@@ -9,6 +11,8 @@
 \usage{
 first(x, n=1, ...)
 last(x, n=1, ...)
+first(x, n=1, ...) <- value
+last(x, n=1, ...) <- value
 }
 \arguments{
   \item{x}{data object}
@@ -17,6 +21,7 @@
           matrix or data frame or lines for a function. If negative,
           all but the 'n' last/first number of elements of 'x'.}
    \item{...}{arguments to be passed to or from other methods.}
+   \item{value}{a vector of values to be assigned (should be of length \code{n})}
 }
 \value{
   An object (usually) like 'x' but generally smaller.
@@ -36,20 +41,37 @@
 first(v)
 last(v)
 
+first(v) <- 9
+v
+
+last(v) <- 20
+v
+
 ## and for lists
 l <- list(a=1, b=2, c=3)
 first(l)
 last(l)
 
+first(l) <- "apple"
+last(l)  <- "bannana"
+l
+
 ## and data.frames
 df <- data.frame(a=1:2, b=3:4, c=5:6)
 first(df)
 last(df)
 
+first(df) <- factor(c("red","green"))
+last(df) <- list(c(20,30)) # note the enclosing list!
+df
+
 ## and matrixes
 m <- as.matrix(df)
 first(m)
 last(m)
 
+first(m) <- "z"
+last(m)  <- "q"
+m
 }
 \keyword{ manip }