stopifnot                package:base                R Documentation

Ensure the `Truth' of R Expressions

Description:

     If any of the expressions in `...' are not `all' `TRUE', `stop' is
     called, producing an error message indicating the first element of
     `...' which was not true.

Usage:

     stopifnot(...)

Arguments:

     ...: any number of (`logical') R expressions which should evaluate
          to `TRUE'.

Details:

     `stopifnot(A, B)' is conceptually equivalent to `{ if(!all(A))
     stop(...) ; if(!all(B)) stop(...) }'.

Value:

     (`NULL' if all statements in `...' are `TRUE'.)

See Also:

     `stop', `warning'.

Examples:

     stopifnot(1 == 1, all.equal(pi, 3.14159265), 1 < 2) # all TRUE

     m <- matrix(c(1,3,3,1), 2,2)
     stopifnot(m == t(m), diag(m) == rep(1,2)) # all(.) |=>  TRUE

     options(error = expression(NULL))# "disable stop(.)"  << Use with CARE! >>

     stopifnot(all.equal(pi, 3.141593),  2 < 2, all(1:10 < 12), "a" < "b")
     stopifnot(all.equal(pi, 3.1415927), 2 < 2, all(1:10 < 12), "a" < "b")

     options(error = NULL)# revert to default error handler

