[R] re-ordering a vector by name

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From: Liaw, Andy (andy_liaw@merck.com)
Date: Sat 08 May 2004 - 07:15:44 EST


Message-id: <3A822319EB35174CA3714066D590DCD504AF7D48@usrymx25.merck.com>

Dear R-help,

Let's say `x1' and `x2' are very long vectors (length=5e5, say) with same
set of names but in different order. If I want to sort `x2' in the order of
`x1', I would do

  x2[names(x1)]

but the amount of time that takes is quite prohibitive! Does anyone have
any suggestion on a more efficient way to do this?

If the two vectors are exactly the same length (as I said above), sorting
both by names would probably be the fastest. However, if the two vectors
differ in length (and the names for the shorter one are a subset of names of
the longer one) then that doesn't work...

Best,
Andy

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