/// \file
/// \ingroup tutorial_dataframe
/// \notebook -draw
/// This tutorial shows how to write out datasets in ROOT formatusing the RDataFrame
/// \macro_code
///
/// \date April 2017
/// \author Danilo Piparo

// A simple helper function to fill a test tree: this makes the example
// stand-alone.
void fill_tree(const char *treeName, const char *fileName)
{
   ROOT::RDataFrame d(10000);
   int i(0);
   d.Define("b1", [&i]() { return i; })
      .Define("b2",
              [&i]() {
                 float j = i * i;
                 ++i;
                 return j;
              })
      .Snapshot(treeName, fileName);
}

int doit()
{
   // We prepare an input tree to run on
   auto fileName = "df007_snapshot.root";
   auto outFileName = "df007_snapshot_output.root";
   auto outFileNameAllColumns = "df007_snapshot_output_allColumns.root";
   auto treeName = "myTree";
   fill_tree(treeName, fileName);

   return 0;
}

int df007_snapshot() {
  while (1)
    doit();
}