title: How can I reorder the rows of a matrix, data.frame or vector according to another one
body: <pre><code>test1 &lt;- as.matrix(c(1, 2, 3, 4, 5))
  row.names(test1) &lt;- c("a", "d", "c", "b", "e") 
  
  test2 &lt;- as.matrix(c(6, 7, 8, 9, 10))
  row.names(test2) &lt;- c("e", "d", "c", "b", "a") 
  
    test1
    [,1]
  a    1
  d    2
  c    3
  b    4
  e    5
  
   test2
    [,1]
  e    6
  d    7
  c    8
  b    9
  a   10
  </code></pre>
  
  <p>How can I reorder test2 so that the rows are in the same order as test1? e.g.</p>
  
  <pre><code> test2
    [,1]
  a    10
  d    7
  c    8
  b    9
  e    6
  </code></pre>
  
  <p>I tried to use the reorder function with: reorder (test1, test2) but I could not figure out the correct syntax. I see that reorder takes a vector, and I'm here using a matrix. My real data has one character vector and another as a data.frame. I figured that the data structure would not matter too much for this example above, I just need help with the syntax and can adapt it to my real problem.</p>