title: sparse.model.matrix loses rows in R
body: <p>I am working on regular <code>data.frame</code> that looks to be to big for <code>glm</code> function so I've decided I'll work on a sparse represantation of a model matrix so I could put this sparse matrix into <code>glmnet</code> function. But <code>sparse.model.matrix</code> looks like to drops some rows from original matrix. Any idea why that happens and any solution how to avoid that?
  Code below:</p>
  
  <pre><code>&gt; mm &lt;- sparse.model.matrix(~clicks01+kl_tomek*bc1+hours+plec+1, 
  data = daneOst)
  &gt; dim(mm)
  [1] 1253223     292
  &gt; dim(daneOst)
  [1] 1258836       6
  </code></pre>