Test if two `data.table`s point to the same memory location
data.table, r
Solution
You can use `data.table::address` for this
> address(DT1)
[1] "0x10336c230"
> address(DT2)
[1] "0x10336c230"
> address(DT3)
[1] "0x10336cb50"
Problem
Let's have: ``` DT1 <- data.table(iris) DT2 <- DT1 # both reference the same memory location though DT3 <- copy(DT1) ``` Question: Is there a way to check that `DT2` keeps referencing the same memory location as `DT1`? Something like this pseudo-function: ``` mem.identical(DT2, DT1) # should return TRUE mem.identical(DT3, DT1) # should return FALSE ``` Unfortunately, `identical` or `all.equal` don't work for this purpose, because ``` identical(DT1,DT3) # gives TRUE ``` Only after introducing some change, the difference can be detected using `identical`: ``` DT1[,Test:=1] # introduces change to DT1 directly, to DT2 indirectly identical(DT1,DT2) # TRUE - proves that DT2 is linked with DT1 identical(DT1,DT3) # FALSE - DT1 and DT3 are clearly decoupled ```