Question

is there a way to test whether two objects are identical in the R language?

For clarity: I do not mean identical in the sense of the identical function,
which compares objects based on certain properties like numerical values or logical values etc.

I am really interested in object identity, which for example could be tested using the is operator in the Python language.

Answer 1

UPDATE: A more robust and faster implementation of address(x) (not using .Internal(inspect(x))) was added to data.table v1.8.9. From NEWS :

New function address() returns the address in RAM of its argument. Sometimes useful in determining whether a value has been copied or not by R, programatically.

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There’s probably a neater way but this seems to work.

address = function(x) substring(capture.output(.Internal(inspect(x)))[1],2,17)
x = 1
y = 1
z = x
identical(x,y)
# [1] TRUE
identical(x,z)
# [1] TRUE
address(x)==address(y)
# [1] FALSE
address(x)==address(z)
# [1] TRUE

You could modify it to work on 32bit by changing 17 to 9.