lapply                 package:base                 R Documentation

Apply a Function over a List or Vector

Description:

     `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' also accepting
     vectors as `X', and returning a vector or array with `dimnames' if
     appropriate.

Usage:

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

Arguments:

       X: list or vector to be used.

     FUN: the function to be applied. 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 if
          possible?

USE.NAMES: logical; if `TRUE' and if `X' is character, use `X' as
          `names' for the result unless it had names already.

See Also:

     `apply', `tapply'.

Examples:

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

