First, we have to import some libraries. "rootpy" is a pythonic wrapper around the ROOT library. In this example, we will use this library instead of the more low-level approach of directly importing "ROOT" and using helpers from "root_numpy".

import numpy as np
from rootpy.plotting import Hist2D, Canvas

Welcome to JupyROOT 6.18/00

We then create a simple 2D histogram over two dimensional random data and plot the output.

# Create output canvas
canvas = Canvas()

# Fill a ROOT histogram from a NumPy array
hist = Hist2D(20, -3, 3, 20, -3, 3)
hist.fill_array(np.random.randn(1000000, 2))

# Draw histogram into canvas
hist.Draw('LEGO2')

# Draw canvas
canvas.Draw()

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