title: De-summarize a dataframe with a column that contains lists in R
body: <p>I have a question about de-summarize a dataframe in R. I have the following dataframe:</p>
  <pre><code>  A  B
    ----
    X  c(1,2,4)
    C  c(1,4,3)
    V  c(5,3,2)
    B  c(2,4,5,6)
  </code></pre>
  <p>So, in the B column are vectors.
  I want to turn this dataframe into the following:</p>
  <pre><code>  B  A
    ----
    1  X
    1  C
    2  X
    2  V
    2  B
    3  C
    3  V
    4  X
    4  C
    4  B
    5  B
    6  B
  </code></pre>
  <p>Maybe someone has an idea how I can convert this table?</p>
  <p>Kind regards</p>