drop {base}R Documentation

Drop Redundant Extent Information


Delete the dimensions of an array which have only one level.





an array (including a matrix).


If x is an object with a dim attribute (e.g., a matrix or array), then drop returns an object like x, but with any extents of length one removed. Any accompanying dimnames attribute is adjusted and returned with x: if the result is a vector the names are taken from the dimnames (if any). If the result is a length-one vector, the names are taken from the first dimension with a dimname.

Array subsetting ([) performs this reduction unless used with drop = FALSE, but sometimes it is useful to invoke drop directly.

See Also

drop1 which is used for dropping terms in models, and droplevels used for dropping unused levels from a factor.


dim(drop(array(1:12, dim = c(1,3,1,1,2,1,2)))) # = 3 2 2
drop(1:3 %*% 2:4)  # scalar product

[Package base version 4.4.0 Index]