%%cpp -d
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);
}

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);

ROOT::RDataFrame d(treeName, fileName);

auto d_cut = d.Filter("b1 % 2 == 0");

auto d2 = d_cut.Define("b1_square", "b1 * b1")
             .Define("b2_vector",
                     [](float b2) {
                        std::vector<float> v;
                        for (int i = 0; i < 3; i++)
                           v.push_back(b2 * i);
                        return v;
                     },
                     {"b2"});

d2.Snapshot(treeName, outFileName, {"b1", "b1_square", "b2_vector"});

TFile f1(outFileName);
auto t = f1.Get<TTree>(treeName);
std::cout << "These are the columns b1, b1_square and b2_vector:" << std::endl;
for (auto branch : *t->GetListOfBranches()) {
   std::cout << "Branch: " << branch->GetName() << std::endl;
}
f1.Close();

d2.Snapshot(treeName, outFileNameAllColumns);

TFile f2(outFileNameAllColumns);
t = f2.Get<TTree>(treeName);
std::cout << "These are all the columns available to this dataframe:" << std::endl;
for (auto branch : *t->GetListOfBranches()) {
   std::cout << "Branch: " << branch->GetName() << std::endl;
}
f2.Close();

auto snapshot_df = d2.Snapshot<int>(treeName, outFileName, {"b1_square"});
auto h = snapshot_df->Histo1D();
auto c = new TCanvas();
h->DrawClone();

return 0;

gROOT->GetListOfCanvases()->Draw()