ifelse                 package:base                 R Documentation

Conditional Element Selection

Description:

     `ifelse' returns a value with the same shape as `test' which is
     filled with elements selected from either `yes' or `no' depending
     on whether the element of `test' is `TRUE' or `FALSE'. If `yes' or
     `no' are too short, their elements are recycled.

Usage:

     ifelse(test, yes, no)

Arguments:

    test: a logical vector

     yes: return values for true elements of `test'.

      no: return values for false elements of `test'.

See Also:

     `if'.

Examples:

     x <- c(6:-4)
     sqrt(x)#- gives warning
     sqrt(ifelse(x >= 0, x, NA))# no warning

     ## Note: the following also gives the warning !
     ifelse(x >= 0, sqrt(x), NA)

