R: Test if an Object is Not Sorted: Test if an Object is Not Sorted


Test if an object is not sorted (in increasing order), without the cost of sorting it.


is.unsorted(x, na.rm = FALSE, strictly = FALSE)



an R object with a class or a numeric, complex, character, logical or raw vector.


logical. Should missing values be removed before checking?


logical indicating if the check should be for strictly increasing values.


A length-one logical value. All objects of length 0 or 1 are sorted. Otherwise, the result will be NA except for atomic vectors and objects with an S3 class (where the >= or > method is used to compare x[i] with x[i-1] for i in 2:length(x)) or with an S4 class where you have to provide a method for is.unsorted().


This function is designed for objects with one-dimensional indices, as described above. Data frames, matrices and other arrays may give surprising results.

Support for raw vectors was added in R 3.1.0.

See Also

sort, order.

Questions? Problems? Suggestions? or email at ian@mutexlabs.com.

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