title: How to fix: "Error in CA(dt, graph = FALSE) : The following variables are not quantitative Var1"
body: <p>I'm trying to use correspondence analysis in R. It seems like the first argument of function "CA" in FactoMineR must be a contingency table. "dt" is a contingency table, but it returns that the variables are not quantitative. </p>
  
  <p>One of the levels of X1 is empty, I dont know if this is a problem in Correspondence Analysis </p>
  
  <pre><code>library("FactoMineR")
  tab1 &lt;- table(as.factor(df$X1),as.factor(df$X2))
  dt &lt;- as.table(as.matrix(tab1))
  res.ca &lt;- CA(dt, graph = FALSE)
  </code></pre>
  
  <p>The output is:</p>
  
  <pre><code>Error in CA(tab1, graph = FALSE) : 
  The following variables are not quantitative:  Var1
  The following variables are not quantitative:  Var2
  </code></pre>