For example to create a histogram with variable bin width, the constructor needs a pointer to the array of the lowEdges (xbins).
TH1D::TH1D(const char* name, const char* title, Int_t nbinsx, const Float_t* xbins)
To make pyRoot understand the pointer use the array class.
from ROOT import * from array import array binLowE = [2,4,9,15,20,22] uniformTau = TH1D("uniformTau","",5,array('d',binLowE))