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I am using rank(a, ties.method="max") to rank a. But I am not quite sure what does ties.method="max" do. Can you please help?

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Ties.method specifies the method rank uses to break ties. Suppose you have a vector c(1,2,3,3,4,5). It's obvious that 1 is first, and 2 is second. However, it's not clear what ranks should be assigned to the first and second 3s. Ties.method determines how this is done. There are a few options:

  • average assigns each tied element the "average" rank. The ranks would therefore be 1, 2, 3.5, 3.5, 5, 6
  • first lets the "earlier" entry "win", so the ranks are in numerical order (1,2,3,4,5,6)

  • min assigns every tied element to the lowest rank, so you get 1,2,3,3,5,6

  • max does the opposite: tied elements get the highest rank (1,2,4,4,5,6)

  • random breaks ties randomly, so you'd get either (1,2,3,4,5,6) or (1,2,4,3,5,6).

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  • $\begingroup$ Thank you very much! Your answer helped me solve my problem! Thank you again! $\endgroup$ – Joy Aug 9 '12 at 18:24
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    $\begingroup$ No problem. You may already know this, but ?command will print the help for a command. $\endgroup$ – Matt Krause Aug 12 '12 at 3:52

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