Less than Greater than signs in pyscript

I am trying to test this code on the webpage

https://medium.com/analytics-vidhya/pyscript-use-python-code-in-html-f7c8b49486a4

When I test this code it looks like it is complaining about the "<" sign inside the py-script tag. Do I need some type of escape character here?

<head>
    <title>Matplotlib</title>
    <meta charset="utf-8">

    <link rel="stylesheet" href="https://pyscript.net/alpha/pyscript.css" />
    <script defer src="https://pyscript.net/alpha/pyscript.js"></script>
    <py-env>
        - matplotlib
    </py-env>
</head>

<body>
    <div id="mpl"></div>
    <py-script output="mpl">
import matplotlib.pyplot as plt
import matplotlib.tri as tri
import numpy as np

# First create the x and y coordinates of the points.
n_angles = 36
n_radii = 8
min_radius = 0.25
radii = np.linspace(min_radius, 0.95, n_radii)

angles = np.linspace(0, 2 * np.pi, n_angles, endpoint=False)
angles = np.repeat(angles[..., np.newaxis], n_radii, axis=1)
angles[:, 1::2] += np.pi / n_angles

x = (radii * np.cos(angles)).flatten()
y = (radii * np.sin(angles)).flatten()
z = (np.cos(radii) * np.cos(3 * angles)).flatten()

# Create the Triangulation; no triangles so Delaunay triangulation created.
triang = tri.Triangulation(x, y)

# Mask off unwanted triangles.
triang.set_mask(np.hypot(x[triang.triangles].mean(axis=1),
y[triang.triangles].mean(axis=1)) < min_radius) fig1, ax1=plt.subplots() ax1.set_aspect('equal') tpc=ax1.tripcolor(triang, z, shading='flat' )
fig1.colorbar(tpc) ax1.set_title('tripcolor of Delaunay triangulation, flat shading') fig1 </py-script>
</body>

</html>

Below is the error I am getting. How do I address the operator issue or am I wrong and issue is else where?

JsException(PythonError: Traceback (most recent call last): File "/lib/python3.10/site-packages/_pyodide/_base.py", line 421, in eval_code CodeRunner( File "/lib/python3.10/site-packages/_pyodide/_base.py", line 237, in __init__ self.ast = next(self._gen) File "/lib/python3.10/site-packages/_pyodide/_base.py", line 141, in _parse_and_compile_gen mod = compile(source, filename, mode, flags | ast.PyCF_ONLY_AST) File "", line 24 y[triang.triangles].mean(axis=1))< min_radius) fig1, ax1=plt.subplots() ax1.set_aspect('equal') tpc=ax1.tripcolor(triang, z, shading='flat' ) ^^^^ SyntaxError: invalid syntax )

Solution

You have a number of source code lines that are folded together. This causes Python syntax errors.

Replace starting at # Mask of unwanted triangles with this:

# Mask off unwanted triangles.
triang.set_mask(np.hypot(x[triang.triangles].mean(axis=1),
y[triang.triangles].mean(axis=1)) < min_radius)
fig1, ax1=plt.subplots()
ax1.set_aspect('equal')
tpc=ax1.tripcolor(triang, z, shading='flat' )
fig1.colorbar(tpc)
ax1.set_title('tripcolor of Delaunay triangulation, flat shading')
fig1
</py-script>

The program will generate an image like this: