title: match row names of two data frames and subset only matching rows in R
body: <p>I would  like to subset &quot;z&quot; data frame based on rows from &quot;b&quot; data frame</p>
  <pre><code>&gt;z
      Fox Prox Sox
  ABC 1   2    3
  DEF 1   1    0
  GHI 1   0    2
  ABD 1   3    0
  AAB 2   3    2
  
  &gt;b
  ABC 1
  DEF 7
  ABD 1
  
  &gt;output
     Fox Prox Sox
  ABC 1   2    3
  DEF 1   1    0
  AAD 2   3    2
  </code></pre>