# c

0th

Percentile

##### Combine Values into a Vector or List

This is a generic function which combines its arguments.

The default method combines its arguments to form a vector. All arguments are coerced to a common type which is the type of the returned value, and all attributes except names are removed.

Keywords
manip
##### Usage
## S3 Generic function
c(…)# S3 method for default
c(…, recursive = FALSE, use.names = TRUE)
##### Arguments

objects to be concatenated.

recursive

logical. If recursive = TRUE, the function recursively descends through lists (and pairlists) combining all their elements into a vector.

use.names

logical indicating if names should be preserved.

##### Details

The output type is determined from the highest type of the components in the hierarchy NULL < raw < logical < integer < double < complex < character < list < expression. Pairlists are treated as lists, whereas non-vector components (such names and calls) are treated as one-element lists which cannot be unlisted even if recursive = TRUE.

Note that factors are treated only via their internal integer codes; one proposal has been to use

   c.factor <- function(..., recursive=TRUE) unlist(list(...), recursive=recursive)

if factor concatenation by c() should give a factor.

c is sometimes used for its side effect of removing attributes except names, for example to turn an array into a vector. as.vector is a more intuitive way to do this, but also drops names. Note that methods other than the default are not required to do this (and they will almost certainly preserve a class attribute).

This is a primitive function.

##### Value

NULL or an expression or a vector of an appropriate mode. (With no arguments the value is NULL.)

##### S4 methods

This function is S4 generic, but with argument list (x, ...).

##### References

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

unlist and as.vector to produce attribute-free vectors.
library(base) # NOT RUN { c(1,7:9) c(1:5, 10.5, "next") ## uses with a single argument to drop attributes x <- 1:4 names(x) <- letters[1:4] x c(x) # has names as.vector(x) # no names dim(x) <- c(2,2) x c(x) as.vector(x) ## append to a list: ll <- list(A = 1, c = "C") ## do *not* use c(ll, d = 1:3) # which is == c(ll, as.list(c(d = 1:3)) ## but rather c(ll, d = list(1:3)) # c() combining two lists c(list(A = c(B = 1)), recursive = TRUE) c(options(), recursive = TRUE) c(list(A = c(B = 1, C = 2), B = c(E = 7)), recursive = TRUE) # }