[R-gregmisc-users] SF.net SVN: r-gregmisc: [1096] trunk/gdata

[<gg...@us...>]

Revision: 1096
          http://svn.sourceforge.net/r-gregmisc/?rev=1096&view=rev
Author:   ggorjan
Date:     2007-06-06 03:19:15 -0700 (Wed, 06 Jun 2007)

Log Message:
-----------
drop levels as suggested by Brian Ripley

Modified Paths:
--------------
    trunk/gdata/R/drop.levels.R
    trunk/gdata/man/drop.levels.Rd

Modified: trunk/gdata/R/drop.levels.R
===================================================================
--- trunk/gdata/R/drop.levels.R	2007-06-06 10:17:52 UTC (rev 1095)
+++ trunk/gdata/R/drop.levels.R	2007-06-06 10:19:15 UTC (rev 1096)
@@ -1,13 +1,13 @@
 
 drop.levels  <- function(x, reorder=TRUE, ...)
-  UseMethod("drop.levels", x=x)
+  UseMethod("drop.levels")
 
 drop.levels.default <- function(x, reorder=TRUE, ...)
   x
 
 drop.levels.factor <- function(x, reorder=TRUE, ...)
 {
-  x <- factor(x)
+  x <- x[, drop=TRUE]
   if(reorder) x <- reorder(x, ...)
   x
 }

Modified: trunk/gdata/man/drop.levels.Rd
===================================================================
--- trunk/gdata/man/drop.levels.Rd	2007-06-06 10:17:52 UTC (rev 1095)
+++ trunk/gdata/man/drop.levels.Rd	2007-06-06 10:19:15 UTC (rev 1096)
@@ -1,9 +1,9 @@
 % $Id$
-%
+
 \name{drop.levels}
 \alias{drop.levels}
 \title{Drop unused factor levels}
-\description{Drop unused levels in a factor.}
+\description{Drop unused levels in a factor}
 \usage{
 drop.levels(x, reorder=TRUE, ...)
 }
@@ -11,22 +11,24 @@
   \item{x}{object to be processed}
   \item{reorder}{should factor levels be reordered using
     \code{\link{reorder.factor}}?}
-  \item{...}{additional arguments to \code{reorder.factor}}
+  \item{...}{additional arguments to \code{\link{reorder.factor}}}
 }
 
 \details{
 
 \code{drop.levels} is a generic function, where default method does
-nothing, while method for factor \code{s} drops all unused levels. There
-are also convinient methods for \code{list} and \code{data.frame}, where
-all unused levels are droped in all factors (one by one) in a
+nothing, while method for factor \code{s} drops all unused levels. Drop
+is done with \code{x[, drop=TRUE]}.
+
+There are also convenient methods for \code{list} and \code{data.frame},
+where all unused levels are dropped in all factors (one by one) in a
 \code{list} or a \code{data.frame}.
 
 }
 
-\value{a data frame}
+\value{Input object without unused levels.}
 
-\author{Jim Rogers \email{jam...@pf...}}
+\author{Jim Rogers \email{jam...@pf...} and Gregor Gorjanc}
 
 \examples{
 


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