[R-gregmisc-users] SF.net SVN: r-gregmisc:[1949] trunk/gtools

[<wa...@us...>]

Revision: 1949
          http://sourceforge.net/p/r-gregmisc/code/1949
Author:   warnes
Date:     2015-04-23 21:47:48 +0000 (Thu, 23 Apr 2015)
Log Message:
-----------
- The 'q' argument to quantcut()'s 'q' now accept an integer
  indicating the number of equally spaced quantile groups to
  create. (Suggestion and patch submitted by Ryan C. Thompson.)

Modified Paths:
--------------
    trunk/gtools/R/quantcut.R
    trunk/gtools/man/quantcut.Rd

Modified: trunk/gtools/R/quantcut.R
===================================================================
--- trunk/gtools/R/quantcut.R	2015-04-23 21:23:36 UTC (rev 1948)
+++ trunk/gtools/R/quantcut.R	2015-04-23 21:47:48 UTC (rev 1949)
@@ -1,7 +1,10 @@
 # $Id$
 
-quantcut <- function(x, q=seq(0,1,by=0.25), na.rm=TRUE, ... )
+quantcut <- function(x, q=4, na.rm=TRUE, ... )
   {
+    if(length(q)==1)
+        q <- seq(0,1, length.out=q+1)
+    
     quant <- quantile(x, q, na.rm=na.rm)
     dups <- duplicated(quant)
     if(any(dups))

Modified: trunk/gtools/man/quantcut.Rd
===================================================================
--- trunk/gtools/man/quantcut.Rd	2015-04-23 21:23:36 UTC (rev 1948)
+++ trunk/gtools/man/quantcut.Rd	2015-04-23 21:47:48 UTC (rev 1949)
@@ -13,8 +13,10 @@
 %- maybe also `usage' for other objects documented here.
 \arguments{
   \item{x}{ Continous variable. }
-  \item{q}{ Vector of quantiles used for creating groups. Defaults to
-    \code{seq(0, 1, by=0.25)}.  See \code{\link{quantile}} for details. }
+  \item{q}{ Either a integer number of equally spaced quantile groups to
+    create, or a vector of quantiles used for creating groups. Defaults to
+    \code{q=4} which is equivalent to \code{q=seq(0, 1, by=0.25)}.
+    See \code{\link{quantile}} for details. }
   \item{na.rm}{ Boolean indicating whether missing values should be
     removed when computing quantiles.  Defaults to TRUE.}
   \item{\dots}{ Optional arguments passed to \code{\link{cut}}. }
@@ -31,7 +33,7 @@
   of quantile intervals.
 }
 \value{
-  Factor variable with one level for each quantile interval given by \code{q}.
+  Factor variable with one level for each quantile interval.
 }
 
 \author{Gregory R. Warnes \email{gr...@wa...}}
@@ -51,13 +53,19 @@
   table(quartiles)
 
   ## cut into deciles
-  deciles <- quantcut( x, seq(0,1,by=0.1) )
-  table(deciles)
+  deciles.1 <- quantcut( x, 10 )
+  table(deciles.1)
+  # or equivalently 
+  deciles.2 <- quantcut( x, seq(0,1,by=0.1) ) 
 
+  \testonly{
+    stopifnot(identical(deciles.1, deciles.2))
+  }
+
   ## show handling of 'tied' quantiles.
   x <- round(x)  # discretize to create ties
   stem(x)        # display the ties
-  deciles <- quantcut( x, seq(0,1,by=0.1) )
+  deciles <- quantcut( x, 10 )
 
   table(deciles) # note that there are only 5 groups (not 10) 
                  # due to duplicates

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