Plotting voxels in Streamlit

voxels.py

"""From https://matplotlib.org/3.1.0/gallery/mplot3d/voxels.html in Streamlit"""
import matplotlib.pyplot as plt
import numpy as np
import streamlit as st

# This import registers the 3D projection, but is otherwise unused.
from mpl_toolkits.mplot3d import Axes3D  # noqa: F401 unused import


@st.cache
def generate_data():
    """Let's put the data in cache so it doesn't reload each time we rerun the script when modifying the slider"""
    # prepare some coordinates
    x, y, z = np.indices((8, 8, 8))

    # draw cuboids in the top left and bottom right corners, and a link between them
    cube1 = (x < 3) & (y < 3) & (z < 3)
    cube2 = (x >= 5) & (y >= 5) & (z >= 5)
    link = abs(x - y) + abs(y - z) + abs(z - x) <= 2

    # combine the objects into a single boolean array
    voxels = cube1 | cube2 | link

    colors = np.empty(voxels.shape, dtype=object)
    colors[link] = 'red'
    colors[cube1] = 'blue'
    colors[cube2] = 'green'

    return voxels, colors

voxels, colors = generate_data()

# let's put sliders to modify view init, each time you move that the script is rerun, but voxels are not regenerated
# TODO : not sure that's the most optimized way to rotate axis but well, demo purpose
azim = st.sidebar.slider("azim", 0, 90, 30, 1)
elev = st.sidebar.slider("elev", 0, 360, 240, 1)

# and plot everything
fig = plt.figure()
ax = fig.gca(projection='3d')
ax.voxels(voxels, facecolors=colors, edgecolor='k')
ax.view_init(azim, elev)

st.pyplot(fig)