Histograming of data in multiple containers, or data that doesn’t fit into computer memory is inconveniant with standard numpy/matplotlib. To work around this, I created a small container class to use histograms as in CERN ROOT style:

h = Histogram(binEdges)
h.Fill(data1)
h.Fill(data2)

bc, bw = getBinCentersAndWidths(binEdges)
hist(bc, bins=binEdges, weights=h.data)

The Hostogram class is part of the matplotlibtools.