title: How to compare and join two dataframes based on the list in another dataframe
body: <p>I have 3 files </p>
  
  <pre><code>F1 - par, ch
  F2 - ch
  F3 - par 
  </code></pre>
  
  <p>So for the par, ch pair in F1, I want to retrieve values from F2 and F3. Then paste row values of par to ch on left.</p>
  
  <p>For example</p>
  
  <p>If par is <code>s</code> &amp; chi is <code>9t</code> ===> result : s9t</p>
  
  <pre><code>s apply(row_values(tab),function(name){ paste(name, tab[,name])})
  </code></pre>
  
  <p>File 1: Containing list Par, ch</p>
  
  <pre><code>F1 &lt;- structure(list(par = structure(c(1L, 2L, 3L, 3L, 4L), .Label = c("a", "b", "c", "d"), class = "factor"), ch = structure(c(2L, 3L, 1L,  4L, 5L), .Label = c("a", "b", "c", "d", "e"), class = "factor")), class = "data.frame", row.names = c(NA, -5L))
  </code></pre>
  
  <p>File 2: Containing ch </p>
  
  <pre><code>F2 &lt;- structure(list(ch = structure(c(2L, 3L, 1L, 4L, 5L), .Label = c("a", "b", "c", "d", "e"), class = "factor"), c1 = structure(c(3L, 
  2L, 3L, 4L, 1L), .Label = c("9n", "9NA", "9s", "9t"), class = "factor"), c2 = structure(c(2L, 3L, 1L, 4L, 5L), .Label = c("11f", "11p", "11t", "11x", "11z"), class = "factor")), class = "data.frame", row.names = c(NA, -5L))
  </code></pre>
  
  <p>File 3: Containing par</p>
  
  <pre><code>F3 &lt;- structure(list(par = structure(c(1L, 2L, 3L, 3L, 4L), .Label = c("a", "b", "c", "d"), class = "factor"), c1 = structure(c(4L, 5L, 3L, 2L, 1L), .Label = c("c", "n", "r", "s", "t"), class = "factor"), c2 = structure(c(4L, 2L, 1L, 3L, 4L), .Label = c("e", "r", "s", "t"), class = "factor")), class = "data.frame", row.names = c(NA, -5L))
  </code></pre>
  
  <p>result --> paste row values of par to row values of ch on left (for the par, ch pair in F1)</p>
  
  <pre><code>result &lt;- structure(list(ch = structure(c(2L, 3L, 1L, 4L, 5L), .Label = c("a", "b", "c", "d", "e"), class = "factor"), c1 = structure(c(4L, 5L, 3L, 2L, 1L), .Label = c("c9n", "n9t", "r9s", "s9s", "t9NA"), class = "factor"), c2 = structure(c(4L, 2L, 1L, 3L, 5L), .Label = c("e11f", "r11t", "s11x", "t11p", "t11z"), class = "factor")), class = "data.frame", row.names = c(NA, -5L))
  </code></pre>