lapply {base}R Documentation

Apply a Function over a List or Vector


lapply returns a list of the same length as X. Each element of which is the result of applying FUN to the corresponding element of X.

sapply is a “user-friendly” version of lapply by default returning a vector or matrix if appropriate.

replicate is a wrapper for the common use of sapply for repeated evaluation of an expression (which will usually involve random number generation).


lapply(X, FUN, ...)
sapply(X, FUN, ..., simplify = TRUE, USE.NAMES = TRUE)

replicate(n, expr, simplify = TRUE)


X list or (atomic) vector to be used.
FUN the function to be applied to each element of X. In the case of functions like +, %*%, etc., the function name must be quoted.
... optional arguments to FUN.
simplify logical; should the result be simplified to a vector or matrix if possible?
USE.NAMES logical; if TRUE and if X is character, use X as names for the result unless it had names already.
n number of replications.
expr expression to evaluate repeatedly.


Function FUN must be able to accept as input any of the elements of X. If the latter is an atomic vector, FUN will always be passed a length-one vector.

Simplification in sapply is only attempted if X has length greater than zero and if the return values from all elements of X are all of the same (positive) length. If the common length is one the result is a vector, and if greater than one is a matrix with a column corresponding to each element of X.

The mode of the simplified answer is chosen to accommodate the modes of all the values returned by the calls to FUN: see unlist.

if X has length 0, the return value of sapply is always a 0-length list.


sapply(*, simplify = FALSE, USE.NAMES = FALSE) is equivalent to lapply(*).


Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.

See Also

apply, tapply.


x <- list(a = 1:10, beta = exp(-3:3), logic = c(TRUE,FALSE,FALSE,TRUE))
# compute the list mean for each list element
# median and quartiles for each list element
lapply(x, quantile, probs = 1:3/4)
sapply(x, quantile)
i39 <- sapply(3:9, seq) # list of vectors
sapply(i39, fivenum)

hist(replicate(100, mean(rexp(10))))

[Package base version 2.2.1 Index]