numeric
Numeric Objects

### Description

Creates or tests for objects of mode numeric.

### Usage

    numeric(length = 0L)
    as.numeric(x, ...)
    is.numeric(x)
    ## S3 method for class 'Date':
    is.numeric(x)
    ## S3 method for class 'POSIXt':
    is.numeric(x)
    ## S3 method for class 'difftime':
    is.numeric(x)

### Arguments

x | any object.
... | other arguments to pass to or from future functions.
length | an integer giving the length of the returned object.

### Details

If you want a factor to be treated as integer, use as.integer.
Coercing to a simple object of mode "numeric" is different from setting the mode attribute using mode(myobject) <- "numeric". While setting the mode attribute changes the mode of myobject, it leaves all other attributes unchanged (so a matrix stays a matrix, for example).
The value of as.numeric(myobject) has no attributes.
Value

numeric | returns vector of a simple object of mode "numeric" and the length specified. The storage mode is "double". If length is greater than 0, the values in this vector are 0.
is.numeric | returns FALSE if x is an object of class Date, POSIXt, or difftime. Otherwise, it returns TRUE if x has mode "numeric" and FALSE if it does not. Its behavior is unaffected by any attributes of x. For example, x could be a numeric array (in contrast to the behavior of is.vector).
as.numeric | returns a vector like x, but with storage mode "double", if x is a simple object of mode "numeric". Otherwise, as.numeric returns a numeric object of the same length as x and with data resulting from coercing the elements of x to mode "numeric".

if x can not be coerced to mode "numeric", NAs are introduced.
Background
When x is of mode "numeric", the data of x can be stored as integers or double precision floating point numbers, and storage.mode(x) is "integer" or "double", respectively.
Normally, all numeric constants that appear in expressions are read with mode numeric and storage mode double. This distinction is relevant only when you use the interface to languages like C or Fortran.
The class of simple objects has no attributes. In most expressions, it is not necessary to ensure explicitly that data are of a particular mode.
References
Becker, R. A., Chambers, J. M., and Wilks, A. R. 1988. The New S Language. Pacific Grove, CA: Wadsworth & Brooks/Cole Advanced Books and Software.
See Also
mode, .Fortran, double, single, vector, integer, Date, POSIXt, difftime.
Examples

    x <- numeric(5)
    y <- c(1, 2, "a")
    is.numeric(y)
    # [1] FALSE
    as.numeric(y)
    # [1]  1  2  NA
    # Warning message: NAs introduced by coercion
    z <- matrix(1:20, nrow = 4)
    is.numeric(z)
    # [1] TRUE
    as.numeric(z)
    # [1]  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20
    mode(z) <- "numeric"  # still a matrix
    is.numeric(Sys.Date())
    is.numeric(Sys.time())
    is.numeric(Sys.time() - as.POSIXct(Sys.Date()))

Package base version 6.1.5-18
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