demo of failing example of hist with np.sqrt

.gitignore

.ipynb_checkpoints/
example.root

README.md

Issue

At the moment there does not seem to be support for NumPy ufuncs for hist histograms created from uproot's .to_hist() API.

Environment Setup

$ git clone git@gist.github.com:ab6ac8677aad2e04738111d0af3e0549.git hist-issue
$ cd hist-issue
$ pyenv virtualenv 3.8.7 hist-issue
$ pyenv activate hist-issue
(hist-issue) $ pip install --upgrade --quiet pip setuptools wheel
(hist-issue) $ cat requirements.txt
hist[plot]==2.2.0
uproot~=4.0.6
uproot3~=3.14.4
jupyter~=1.0
jupyterlab~=2.2
(hist-issue) $ pip install -r requirements.txt

Minimal failing example

(hist-issue) $ python minimal-failing.py
hists in file: ['mass;1']
Traceback (most recent call last):
  File "minimal-failing.py", line 100, in <module>
    main()
  File "minimal-failing.py", line 96, in main
    minimal_failing(root_file)
  File "minimal-failing.py", line 74, in minimal_failing
    sqrt_values = np.sqrt(hist_mass)
TypeError: ufunc 'sqrt' not supported for the input types, and the inputs could not be safely coerced to any supported types according to the casting rule ''safe''

Minimal passing example

(hist-issue) $  python minimal-failing.py pass
np.sqrt gives: [0.         0.         0.         0.         0.         0.36136437
 1.36677301 2.24499357 3.3028363  4.01532338 4.46574546 4.50899645
 4.54050631 4.45316398 4.04590633 3.8036544  3.50747509 3.26808198
 2.91475639 2.61148735 2.36931914 2.15342051 1.73440724 1.6316221
 1.40370282 1.23654795 1.06892428 1.0623001  0.95068096 0.73183709
 0.50208207 0.58183567 0.53861281 0.39997453 0.35529868 0.28219637
 0.20478919 0.18039576 0.19334187 0.07509284 0.         0.
 0.07867583 0.         0.         0.         0.10174972 0.
 0.         0.        ]

minimal-failing.ipynb

minimal-failing.py

import sys

import hist
import numpy as np
import uproot3
import uproot
from hist import Hist


def write_root_file(name="example.root"):
    values = np.array(
        [
            0.0,
            0.0,
            0.0,
            0.0,
            0.0,
            0.1305842101573944,
            1.8680684566497803,
            5.039996147155762,
            10.908727645874023,
            16.122821807861328,
            19.942882537841797,
            20.3310489654541,
            20.61619758605957,
            19.830669403076172,
            16.36935806274414,
            14.46778678894043,
            12.30238151550293,
            10.680359840393066,
            8.495804786682129,
            6.819866180419922,
            5.613673210144043,
            4.6372199058532715,
            3.0081684589385986,
            2.6621906757354736,
            1.9703816175460815,
            1.5290508270263672,
            1.142599105834961,
            1.1284815073013306,
            0.9037942886352539,
            0.5355855226516724,
            0.2520864009857178,
            0.3385327458381653,
            0.2901037633419037,
            0.15997962653636932,
            0.126237154006958,
            0.07963479310274124,
            0.04193861410021782,
            0.0325426310300827,
            0.03738107904791832,
            0.005638935137540102,
            0.0,
            0.0,
            0.006189885549247265,
            0.0,
            0.0,
            0.0,
            0.010353004559874535,
            0.0,
            0.0,
            0.0,
        ]
    )
    edges = np.arange(0, 10000 + 200, 200)

    with uproot3.recreate(name, compression=uproot3.ZLIB(4)) as outfile:
        outfile["mass"] = (values, edges)


def minimal_failing(root_file):
    print(f"hists in file: {root_file.keys()}")
    hist_mass = root_file["mass"].to_hist()
    sqrt_values = np.sqrt(hist_mass)
    print(f"np.sqrt gives: {sqrt_values}")


def minimal_passing(root_file):
    values, edges = root_file["mass"].to_numpy()
    hist_mass = Hist(
        hist.axis.Regular(len(edges) - 1, edges[0], edges[-1], name="mass"),
        storage=hist.storage.Double(),
    )
    hist_mass[:] = values
    sqrt_values = np.sqrt(hist_mass)
    print(f"np.sqrt gives: {sqrt_values}")


def main(input=sys.argv):
    write_root_file("example.root")

    root_file = uproot.open("example.root")
    if input[-1] == "pass":
        minimal_passing(root_file)
    else:
        minimal_failing(root_file)


if __name__ == "__main__":
    main()

requirements.txt

hist[plot]==2.2.0
uproot~=4.0.6
uproot3~=3.14.4
jupyter~=1.0
jupyterlab~=2.2

@henryiii has pointed out this isn't really using the proper API and I should be using

sqrt_values = np.sqrt(hist_mass.values())

Which is already what I'm doing in the minimal_passing example, so that's seem fair. 👍