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Join using on not working when specifying column names #2094
Description
Activity
The lower-case x and y are meaningful there. They should be column names in X. Similarly, a and b should be column names in Y.
The line you found in the code shows the cols of X being selected. Try
names(c(x="A", y="B"))if you're not familiar with that function already. Similarly, the leftcols line soon after shows cols of Y being selected (tryunname(c(x="A", y="B")))...Thanks for the quick response. With this additional info, I've confirmed that everything works. I was getting confused by the fact that the lowercase names matched the table names, so my only suggestion might be to clarify the help text a bit more (the second and third lines of your comment are really helpful).
This example doesn't appear to work.
But the
data.tablehelp foronappears to say that it should work: "As a named character vector, e.g., X[Y, on=c(x="a", y="b")]. This is useful when column names to join by are different between the two tables."From what I can see in the code, it appears that the
onnames are not used when checking is columns are present.