title: join two or more data frames in system R
body: <p>My questions is how can join two or more data frames in system R?</p>
  <p>For example:</p>
  <p>I have two data frames:</p>
  <p>first:</p>
  <pre><code>   x  y  z
  1  3  2  4
  2  4  5  7
  3  5  6  8
  </code></pre>
  <p>second:</p>
  <pre><code>   x  y  z
  1  1  1  1
  2  4  5  7
  </code></pre>
  <p>I need this:</p>
  <pre><code>   x  y  z
  1  3  2  4
  2  4  5  7
  3  5  6  8
  4  1  1  1
  5  4  5  7
  </code></pre>
  <p>I tried to use append for each vector, like this:</p>
  <blockquote>
  <p>for( i in 1:length(first)){</p>
  <pre><code>    mix[[i]]&lt;-append(first[i], second[i])}
  </code></pre>
  <p>f&lt;-do.call(rbind, mix)</p>
  </blockquote>
  <p>But It didn't work like I needed. I didn't get my matrix, i got some different structure.</p>