stopifnot: 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 of the elements of … which were not true.

Usage

stopifnot(…)

Arguments

…

any number of (logical) R expressions, which should evaluate to TRUE.

Value

(NULL if all statements in … are TRUE.)

Details

This function is intended for use in regression tests or also argument checking of functions, in particular to make them easier to read.

stopifnot(A, B) is conceptually equivalent to

 { if(any(is.na(A)) || !all(A)) stop(...);
   if(any(is.na(B)) || !all(B)) stop(...) }

Since R version 3.4.0, when an expression (from …) is not true and is a call to all.equal, the error message will report the (first part of the) differences reported by all.equal(*).

Examples

Run this code

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

op <- options(error = expression(NULL))
# "disabling 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")

# long all.equal() error messages are abbreviated:
stopifnot(all.equal(rep(list(pi),4), list(3.1, 3.14, 3.141, 3.1415)))

options(op)  # revert to previous error handler

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