Update docs and release

NEWS

@@ -1,4 +1,4 @@
-plyr 0.1.5 (2008-XX-XX) ---------------------------------------------------
+plyr 0.1.5 (2008-02-23) ---------------------------------------------------
 
 * colwise now accepts a quoted list as its second argument.  This allows you to specify the names of columns to work on: colwise(mean, .(lat, long))
 * d_ply and a_ply now correctly pass ... to the function

man/colwise-5m.rd

@@ -8,14 +8,42 @@
 \description{
 Turn a function that operates on a vector into a function that operates column-wise on a data.frame
 }
-\usage{colwise(.fun, .if = function(x) TRUE)}
+\usage{colwise(.fun, .cols = function(x) TRUE)}
 \arguments{
 \item{.fun}{function}
-\item{.if}{function that tests columns for inclusion}
+\item{.cols}{either function that tests columns for inclusion, or a quoted object giving which columns to process}
 }
 
 \details{\code{catcolwise} and \code{numcolwise} provide version that only operate
 on discrete and numeric variables respectively}
 
-\examples{}
+\examples{# Count number of missing values
+nmissing <- function(x) sum(is.na(x))
+
+# Apply to every column in a data frame 
+colwise(nmissing)(baseball)
+# This syntax looks a little different.  It is shorthand for the 
+# the following:
+f <- colwise(nmissing)
+f(baseball)
+
+# This is particularly useful in conjunction with d*ply
+ddply(baseball, .(year), colwise(nmissing))
+
+# To operate only on specified columns, supply them as the second
+# argument.  Many different forms are accepted.
+ddply(baseball, .(year), colwise(nmissing, .(sb, cs, so)))
+ddply(baseball, .(year), colwise(nmissing, c("sb", "cs", "so")))
+ddply(baseball, .(year), colwise(nmissing, ~ sb + cs + so))
+
+# Alternatively, you can specify a boolean function that determines
+# whether or not a column should be included
+ddply(baseball, .(year), colwise(nmissing, is.character))
+ddply(baseball, .(year), colwise(nmissing, is.numeric))
+ddply(baseball, .(year), colwise(nmissing, is.discrete))
+
+# These last two cases are particularly common, so some shortcuts are 
+# provided:
+ddply(baseball, .(year), numcolwise(nmissing))
+ddply(baseball, .(year), catcolwise(nmissing))}