Belle II Software light-2406-ragdoll
MCGenTopo.py
1#!/usr/bin/env python3
2
3
10
11from variables.utils import create_aliases
12import variables
13
14
15def mc_gen_topo(n=200):
16 """
17 Gets the list of variables containing the raw topology information of MC generated events.
18 To be specific, the list including the following variables:
19
20 * ``nMCGen``: number of MC generated particles in a given event,
21 * ``MCGenPDG_i`` (i=0, 1, ... n-2, n-1):
22 PDG code of the :math:`{\\rm i}^{\\rm th}` MC generated particle in a given event,
23 * ``MCGenMothIndex_i`` (i=0, 1, ... n-2, n-1):
24 mother index of the :math:`{\\rm i}^{\\rm th}` MC generated particle in a given event.
25
26 .. tip::
27
28 * Internally, ``nMCGen``, ``MCGenPDG_i`` and ``MCGenMothIndex_i`` are just aliases of
29 ``nMCParticles``, ``genParticle(i, varForMCGen(PDG))``
30 and ``genParticle(i, varForMCGen(mcMother(mdstIndex)))``, respectively.
31 * For more details on the variables, please refer to the documentations of
32 :b2:var:`nMCParticles`, :b2:var:`genParticle`, :b2:var:`varForMCGen`,
33 :b2:var:`PDG`, :b2:var:`mcMother`, and :b2:var:`mdstIndex`.
34
35 Parameters:
36 n (int): number of ``MCGenPDG_i``/``MCGenMothIndex_i`` variables. Its default value is 200.
37
38 .. note::
39
40 * To completely examine the topology information of the events in an MC sample,
41 the parameter ``n`` should be greater than or equal to the maximum of ``nMCGen`` in the sample.
42 * Normally, the maximum of ``nMCGen`` in the MC samples at Belle II is less than 200.
43 Hence, if you have no idea about the maximum of ``nMCGen`` in your own MC sample,
44 it is usually a safe choice to use the default parameter value 200.
45 * However, an overlarge parameter value leads to unnecessary waste of disk space and
46 redundant variables with inelegant ``nan`` values.
47 Hence, if you know the maximum of ``nMCGen`` in your own MC sample,
48 it is a better choice to assign the parameter a proper value.
49 """
50 list_of_indexes = [str(i) for i in range(n)]
51 wrapper = 'genParticle({variable}, varForMCGen(PDG))'
52 prefix = 'MCGenPDG'
53 MCGenPDG = create_aliases(list_of_indexes, wrapper, prefix)
54 wrapper = 'genParticle({variable}, varForMCGen(mcMother(mdstIndex)))'
55 prefix = 'MCGenMothIndex'
56 MCGenMothIndex = create_aliases(list_of_indexes, wrapper, prefix)
57 variables.variables.addAlias('nMCGen', 'nMCParticles')
58 list_of_variables = ['nMCGen']
59 for i in range(n):
60 list_of_variables.append(MCGenPDG[i])
61 list_of_variables.append(MCGenMothIndex[i])
62 return list_of_variables