Length of an Object

Description

Get or set the length of vectors (including lists) and factors, and of any other R object for which a method has been defined.

Usage

length(x)
length(x) <- value

Arguments

Details

Both functions are generic: you can write methods to handle specific classes of objects, see InternalMethods.

The replacement form can be used to reset the length of a vector. If a vector is shortened, extra values are discarded and when a vector is lengthened, it is padded out to its new length with NAs.

Value

The length of x as an integer of length 1, if x is (or can be coerced to) a vector or list. Otherwise, length returns NA.

References

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

See Also

nchar for counting the number of characters in character vectors.

Examples

length(diag(4))# = 16 (4 x 4)
length(options())# 12 or more
length(y ~ x1 + x2 + x3)# 3
length(expression(x, {y <- x^2; y+2}, x^y)) # 3