| length | R Documentation |
Get or set the length of vectors (including lists) and factors, and ofany otherR object for which a method has been defined.
length(x)length(x) <- value
x | anR object. For replacement, a vector or factor. |
value | a non-negative integer or double (which will be rounded down). |
Both functions are generic: you can write methods to handle specificclasses of objects, see InternalMethods.length<- has a"factor" method.
The replacement form can be used to reset the length of a vector. Ifa vector is shortened, extra values are discarded and when a vector islengthened, it is padded out to its new length withNAs(nul for raw vectors).
Both are primitive functions.
The default method forlength currently returns a non-negativeinteger of length 1, except for vectors of more than2^31 - 1 elements, when it returns a double.
For vectors (including lists) and factors the length is the number ofelements. For an environment it is the number of objects in theenvironment, andNULL has length 0. For expressions andpairlists (including language objects and dotlists) it is thelength of the pairlist chain. All other objects (including functions)have length one: note that for functions this differs from S.
The replacement form removes all the attributes ofx except itsnames, which are adjusted (and if necessary extended by"").
Package authors have written methods that return a result of lengthother than one (Formula) and that return a vector of typedouble (Matrix), even with non-integer values(earlier versions ofsets). Where a single double value isreturned that can be represented as an integer it is returned as alength-one integer vector.
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988)The New S Language.Wadsworth & Brooks/Cole.
nchar for counting the number of characters in charactervectors,lengths for getting the length of every elementin a list.
length(diag(4)) # = 16 (4 x 4)length(options()) # 12 or morelength(y ~ x1 + x2 + x3) # 3length(expression(x, {y <- x^2; y+2}, x^y)) # 3## from example(warpbreaks)require(stats)fm1 <- lm(breaks ~ wool * tension, data = warpbreaks)length(fm1$call) # 3, lm() and two arguments.length(formula(fm1)) # 3, ~ lhs rhsAdd the following code to your website.
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