On Oct 25, 2011, at 6:07 AM, Samir Benzerfa wrote:
Hi
I have probably a very simple question but I'm going crazy trying to
find
the solution.
I have two data.frames with headers and I'm doing an intersection
between
them by names, such that the intersected data.frames are returned by:
df1[intersect(names (df1), names(df2))] and the same for df2
Now, I want to have all the opposite data that did not intersect. I
tried to
do: df1[-intersect(names (df1), names(df2))] and some other stuff
but it
didn't work.
Right. You cannot use negative indexing with character column
identifiers.
Two methods you can try:
df1[ setdiff( names(df1), names(df2)) ]
df2[ setdiff( names(df2), names(df1)) ]
Or:
df1[!names(df1) %in% names(df2)]
(They both use match() "under the hood" so there would also be a
match() based solution as well.)
--
David Winsemius, MD
West Hartford, CT
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