Rdataframe equivalent of TTree::Scan

ROOT
1

Dear experts,

Is there a rdataframe equivalent to the TTree::Scan? I could not find it on the rdataframe class reference page nor by a simple search in the forum… Thanks.

Dongliang

2

Hi,
Not a 1 to 1 equivalent, but the Display action prints branch contents to screen.
https://root.cern/doc/v616/classROOT_1_1RDF_1_1RInterface.html#aee68f4411f16f00a1d46eccb6d296f01

Why not use TTree::Scan though? :smile:

3

Thanks a lot for the quick reply. I want to have a quick look of the run number and event number of my selected events. I’m using pyroot in Jupyter notebook. Following your suggestion, I can use Display to show one variable, but don’t find an easy way to show multiple… do you have an example for this?

4

Hi,

you can select multiple columns providing them explicitly or via a regular expression matching their names.
For example:

myRdf.Display({"column_0", "column_1", ..., "column_N"});

Cheers,
D

5

Thanks for the example, but I guess this is an example in C++. How to do this in pyroot?

6 
myRdf.Display(("column_0", "column_1", ..., "column_N"))
7

I get following errors:

TypeError Traceback (most recent call last)
in
1 d3a = d3.Define(‘Et2’,‘cQ0+cQ1+cQ6’).Define(‘Et2v’,‘E-Et2’).Filter(‘cQ0>400&&cQ1>300&&cQ6>200&&cQ3<100&&cQ5<100&&cQ18<100’)
----> 2 pp1 = d3a.Filter(‘tID>3’).Display((‘run’,‘evt’))
3 pp1.Print()

TypeError: none of the 3 overloaded methods succeeded. Full details:
ROOT::RDF::RResultPtrROOT::RDF::RDisplay ROOT::RDF::RInterfaceROOT::Detail::RDF::RJittedFilter,void::Display(const vector& columnList, const int& nRows = 5) =>
could not convert argument 1 (none of the 10 overloaded methods succeeded. Full details:
vector::vector() =>
takes at most 0 arguments (2 given)
vector::vector(const allocator& __a) =>
takes at most 1 arguments (2 given)
vector::vector(unsigned long __n, const allocator& __a = std::vector<std::basic_string, std::allocator<std::basic_string > >::allocator_type()) =>
could not convert argument 1 (an integer is required)
vector::vector(unsigned long __n, const string& __value, const allocator& __a = std::vector<std::basic_string, std::allocator<std::basic_string > >::allocator_type()) =>
could not convert argument 1 (an integer is required)
vector::vector(const vector& __x) =>
takes at most 1 arguments (2 given)
vector::vector(vector&& __x) =>
takes at most 1 arguments (2 given)
vector::vector(const vector& __x, const allocator& __a) =>
could not convert argument 1
vector::vector(vector&& __rv, const allocator& __m) =>
could not convert argument 1 (this method can not (yet) be called)
vector::vector(initializer_list __l, const allocator& __a = std::vector<std::basic_string, std::allocator<std::basic_string > >::allocator_type()) =>
could not convert argument 1
vector::vector(__gnu_cxx::__normal_iterator<const experimental::basic_string_view<char,char_traits >,vector<experimental::basic_string_view<char,char_traits > > > __first, __gnu_cxx::__normal_iterator<const experimental::basic_string_view<char,char_traits >,vector<experimental::basic_string_view<char,char_traits > > > __last, const allocator& __a = std::vector<std::basic_string, std::allocator<std::basic_string > >::allocator_type()) =>
could not convert argument 1)
ROOT::RDF::RResultPtrROOT::RDF::RDisplay ROOT::RDF::RInterfaceROOT::Detail::RDF::RJittedFilter,void::Display(experimental::basic_string_view<char,char_traits > columnNameRegexp = “”, const int& nRows = 5) =>
could not convert argument 1
ROOT::RDF::RResultPtrROOT::RDF::RDisplay ROOT::RDF::RInterfaceROOT::Detail::RDF::RJittedFilter,void::Display(initializer_list columnList, const int& nRows = 5) =>
could not convert argument 1 (none of the 3 overloaded methods succeeded. Full details:
initializer_list::initializer_list() =>
takes at most 0 arguments (2 given)
initializer_list::initializer_list(const initializer_list&) =>
takes at most 1 arguments (2 given)
initializer_list::initializer_list(initializer_list&&) =>
takes at most 1 arguments (2 given))

I’m using JupyROOT 6.16/00 on Centos 7. There is no problem to display one variable.

8

Unfortunately, I am afraid this syntax is not yet available and that is why Display is complaining about the type of the tuple argument.

You will need to construct an std::vector<string> from Python and pass that vector as the argument.

v = ROOT.std.vector('std::string')()
for c in 'run','evt':
  v.push_back(c)
pp1 = d3a.Filter('tID>3').Display(v)
1 Like
9

It works. Thanks a lot!

10

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