all.equal: Test if Two Objects are (Nearly) Equal

Description

all.equal(x, y) is a utility to compare R objects x and y testing ‘near equality’. If they are different, comparison is still made to some extent, and a report of the differences is returned. Don't use all.equal directly in if expressions---either use isTRUE(all.equal(....)) or identical if appropriate.

Usage

all.equal(target, current, ...)
"all.equal"(target, current, tolerance = .Machine$double.eps ^ 0.5, scale = NULL, check.attributes = TRUE, ...)
attr.all.equal(target, current, check.attributes = TRUE, check.names = TRUE, ...)

Arguments

target

R object.

current

other R object, to be compared with target.

...

Further arguments for different methods, notably the following two, for numerical comparison:

tolerance

numeric $\ge$ 0. Differences smaller than tolerance are not considered.

scale

numeric scalar > 0 (or NULL). See ‘Details’.

check.attributes

logical indicating if the attributes of target and current (other than the names) should be compared.

check.names

logical indicating if the names(.) of target and current should be compared.

Value

Either TRUE (NULL for attr.all.equal) or a vector of mode "character" describing the differences between target and current.

Warning

Arguments other than target and current should be specified via their full name: this will be required as from R 3.1.0.

Details

all.equal is a generic function, dispatching methods on the target argument. To see the available methods, use methods("all.equal"), but note that the default method also does some dispatching, e.g. using the raw method for logical targets.

Numerical comparisons for scale = NULL (the default) are done by first computing the mean absolute difference of the two numerical vectors. If this is smaller than tolerance or not finite, absolute differences are used, otherwise relative differences scaled by the mean absolute difference.

If scale is positive, absolute comparisons are made after scaling (dividing) by scale.

For complex target, the modulus (Mod) of the difference is used: all.equal.numeric is called so arguments tolerance and scale are available.

The method for the date-time class "POSIXct" by default allows a tolerance of tolerance = 0.001 seconds.

attr.all.equal is used for comparing attributes, returning NULL or a character vector.

References

Chambers, J. M. (1998) Programming with Data. A Guide to the S Language. Springer (for =).

Examples

Run this code

all.equal(pi, 355/113)
# not precise enough (default tol) > relative error

d45 <- pi*(1/4 + 1:10)
stopifnot(
all.equal(tan(d45), rep(1, 10)))          # TRUE, but
all      (tan(d45) == rep(1, 10))         # FALSE, since not exactly
all.equal(tan(d45), rep(1, 10), tolerance = 0)  # to see difference

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