ROOT histogram bins

test_root.py

import ROOT
from test_uproot import vals

if __name__ == "__main__":
    h = ROOT.TH1D("h", "h", 10, 0, 1)

    for v in vals:
        h.Fill(v)

    print("h1")
    for b in range(h.GetNbinsX()+2):
        print("bin={} content={:.2f} error={:.2f} low={}".format(
            b, h.GetBinContent(b), h.GetBinError(b), h.GetBinLowEdge(b)
        ))

    fi = ROOT.TFile.Open("out_uproot.root")
    h2 = fi.Get("h")

    print("h2")
    for b in range(h2.GetNbinsX()+2):
        print("bin={} content={:.2f} error={:.2f} low={}".format(
            b, h2.GetBinContent(b), h2.GetBinError(b), h2.GetBinLowEdge(b)
        ))

test_uproot.py

import numpy as np
from uproot_methods.classes.TH1 import from_numpy
import uproot
from hepaccelerate.backend_cpu import fill_histogram

#data array to put into histogram
vals = [-0.1, 0, 0.2, 0.9, 1.0, 1.1]

def to_th1(hdict, name):
    content = np.array(hdict["contents"])
    content_w2 = np.array(hdict["contents_w2"])
    edges = np.array(hdict["edges"])

    #remove inf/nan just in case
    content[np.isinf(content)] = 0
    content_w2[np.isinf(content_w2)] = 0

    content[np.isnan(content)] = 0
    content_w2[np.isnan(content_w2)] = 0

    #update the error bars
    centers = (edges[:-1] + edges[1:]) / 2.0
    th1 = from_numpy((content, edges))
    th1._fName = name
    #note, fix needed here
    th1._fSumw2[1:-1] = np.array(hdict["contents_w2"])
    th1._fTsumw2 = np.array(hdict["contents_w2"]).sum()
    th1._fTsumwx2 = np.array(hdict["contents_w2"] * centers).sum()
    return th1

if __name__ == "__main__":
    #explicitly include overflow as a bin 1.1
    bins = np.array([0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1], np.float32)
    out_w = np.zeros((len(bins) - 1), np.float32)
    out_w2 = np.zeros((len(bins) - 1), np.float32)

    fill_histogram(np.array(vals, np.float32), np.ones_like(vals, dtype=np.float32), bins, out_w, out_w2)

    h2 = to_th1({
        "contents": out_w,
        "contents_w2": out_w2,
        "edges": bins
    }, name="h2")

    fi = uproot.recreate("out_uproot.root")
    fi["h"] = h2
    fi.close()