Vector of vector

[lietava]

We avoid using vectors of vectors for persistent and messageable data formats, instead we use 2 flat vectors, in your case it would be a vector and another vector which would tell the start entry and number of entries in the 1st vector, related to given trigger. See e.g.

AliceO2/DataFormats/Detectors/FIT/FT0/include/DataFormatsFT0/Digit.h

Lines 110 to 111 in 8ea4ea2

struct Digit {
o2::dataformats::RangeReference<int, int> ref;
as an example of this 2nd vector (the reference to entries of give trigger in the vector of channels
AliceO2/DataFormats/Detectors/FIT/FT0/include/DataFormatsFT0/ChannelData.h

Line 24 in 8ea4ea2

struct ChannelData {
is done via special class
AliceO2/DataFormats/common/include/CommonDataFormat/RangeReference.h

Line 28 in 8ea4ea2

class RangeReference

or its more compact version
AliceO2/DataFormats/common/include/CommonDataFormat/RangeReference.h

Lines 58 to 60 in 8ea4ea2