R: Is an Object 'internally classed'?

is.object {base} | R Documentation

## Is an Object ‘internally classed’?

### Description

A function rather for internal use. It returns `TRUE` if the object `x` has the R internal `OBJECT` bit set, and `FALSE` otherwise. The `OBJECT` bit is set when a `"class"` attribute is added and removed when that attribute is removed, so this is a very efficient way to check if an object has a class attribute. (S4 objects always should.)

### Usage

    is.object(x)

### Arguments

`x` | object to be tested.

### Note

This is a primitive function.

### See Also

`class`, and `methods`.

`isS4`.

### Examples

    is.object(1) # FALSE
    is.object(as.factor(1:3)) # TRUE

[Package base version 3.1.2 Index]