diff --git a/man/fcase.Rd b/man/fcase.Rd index dd3a119110..466f3dfc67 100644 --- a/man/fcase.Rd +++ b/man/fcase.Rd @@ -11,6 +11,11 @@ \item{...}{ A sequence consisting of logical condition (\code{when})-resulting value (\code{value}) \emph{pairs} in the following order \code{when1, value1, when2, value2, ..., whenN, valueN}. Logical conditions \code{when1, when2, ..., whenN} must all have the same length, type and attributes. Each \code{value} may either share length with \code{when} or be length 1. Please see Examples section for further details.} \item{default}{ Default return value, \code{NA} by default, for when all of the logical conditions \code{when1, when2, ..., whenN} are \code{FALSE} or missing for some entries. } } +\details{ +\code{fcase} evaluates each when-value pair in order, until it finds a \code{when} that is \code{TRUE}. It then returns the corresponding \code{value}. During evaluation, \code{value} will be evaluated regardless of whether the corresponding \code{when} is \code{TRUE} or not, which means recursive calls should be placed in the last when-value pair, see \code{Examples}. + +\code{default} is always evaluated, regardless of whether it is returned or not. +} \value{ Vector with the same length as the logical conditions (\code{when}) in \code{...}, filled with the corresponding values (\code{value}) from \code{...}, or eventually \code{default}. Attributes of output values \code{value1, value2, ...valueN} in \code{...} are preserved. } @@ -54,5 +59,13 @@ fcase( x > 5L, 3L, default = 5L ) + +# fcase can be used for recursion, unlike fifelse +# Recursive function to calculate the Greatest Common Divisor +gcd_dt = function(x,y) { + r = x\%\%y + fcase(!r, y, r, gcd_dt(x, y)) # Recursive call must be in the last when-value pair +} +gcd_dt(10L, 1L) } \keyword{ data } diff --git a/man/fifelse.Rd b/man/fifelse.Rd index 4165dd796d..7f03b4e085 100644 --- a/man/fifelse.Rd +++ b/man/fifelse.Rd @@ -15,12 +15,16 @@ } \details{ In contrast to \code{\link[base]{ifelse}} attributes are copied from the first non-\code{NA} argument to the output. This is useful when returning \code{Date}, \code{factor} or other classes. + +Unlike \code{\link[base]{ifelse}}, \code{fifelse} evaluates both \code{yes} and \code{no} arguments for type checking regardless of the result of \code{test}. This means that neither \code{yes} nor \code{no} should be recursive function calls. For recursion, use \code{fcase} instead. } \value{ A vector of the same length as \code{test} and attributes as \code{yes}. Data values are taken from the values of \code{yes} and \code{no}, eventually \code{na}. } \seealso{ \code{\link{fcoalesce}} + + \code{\link{fcase}} } \examples{ x = c(1:4, 3:2, 1:4) @@ -37,5 +41,9 @@ fifelse(c(TRUE,FALSE,TRUE), yes, no) # Example of using the 'na' argument fifelse(test = c(-5L:5L < 0L, NA), yes = 1L, no = 0L, na = 2L) + +# Example showing both 'yes' and 'no' arguments are evaluated, unlike ifelse +fifelse(1 == 1, print("yes"), print("no")) +ifelse(1 == 1, print("yes"), print("no")) } \keyword{ data }