Hist implements the UHI and UHI+ indexing protocols. You can read more about them on the Indexing and Indexing+ pages.

Hist specific details#

Hist implements hist.loc, builtins.sum, hist.rebin, hist.underflow, and hist.overflow from the UHI spec. A locator is provided as well, which simulates the Boost.Histogram C++ .at() indexing using the UHI locator protocol.

Hist allows “picking” using lists, similar to NumPy. If you select with multiple lists, hist instead selects per-axis, rather than group-selecting and reducing to a single axis, like NumPy does. You can use hist.loc(...) inside these lists.


h = Hist(
    hist.axis.Regular(10, 0, 1),
    hist.axis.StrCategory(["a", "b", "c"]),
    hist.axis.IntCategory([5, 6, 7]),

minihist = h[:, [hist.loc("a"), hist.loc("c")], [0, 2]]

# Produces a 3D histgoram with Regular(10, 0, 1) x StrCategory(["a", "c"]) x IntCategory([5, 7])

This feature is considered experimental. Removed bins are not added to the overflow bin currently.