Test Inheritance of an Object

DESCRIPTION:

Returns a logical value or an integer vector indicating from which classes x inherits.

USAGE:

inherits(x, what, which=F) 

REQUIRED ARGUMENTS:

x
any object, possibly but not necessarily having a class attribute.
what
a character vector of possible classes.

OPTIONAL ARGUMENTS:

which
logical flag: if TRUE, specify which classes matched the object; if FALSE, just say whether any classes matched the object.

VALUE:

if which is FALSE, a single logical value. The value is TRUE if any of the classes in the class attribute of x match (exactly) any of the strings in what.
if which is TRUE, an integer vector of the same length as what that contains the position in the class of x that each value in what matches. A zero is returned for elements of what that dont match any element of the class.

SEE ALSO:

.

EXAMPLES:

# the definition of as.factor 
function(x) if(inherits(x,"factor")) x else factor(x) 
inherits(y~x, c("formula", "terms"))