Replace examples with those from the second edition of the AMUSE book

examples/__init__.py

@@ -0,0 +1,65 @@
+"""
+AMUSE examples module
+"""
+
+import inspect
+import importlib
+
+try:
+    from IPython.core.getipython import get_ipython
+    from IPython.terminal.interactiveshell import InteractiveShell
+except ImportError:
+
+    def get_ipython():
+        "N/A, so return None"
+        return None
+
+
+def get(example_name, prefix="amuse.examples"):
+    """
+    Retrieves an AMUSE example.
+    """
+    if prefix is not None:
+        if prefix[-1] != ".":
+            prefix += "."
+    return inspect.getsource(importlib.import_module(f"{prefix}{example_name}"))
+
+
+def to_cell(example_name, prefix="amuse.examples"):
+    """
+    Creates a Jupyter cell from an AMUSE example.
+    Works also for other modules, set prefix to None in that case.
+    """
+
+    contents = get(example_name, prefix=prefix)
+    shell = get_ipython()
+    shell.set_next_input(contents, replace=False)
+
+
+def show(example_name, prefix="amuse.examples"):
+    """
+    Prints the source code of an AMUSE example.
+    """
+    print(get(example_name, prefix=prefix))
+
+
+def run(example_name):
+    """
+    Runs an AMUSE example.
+    """
+    prefix = "amuse.examples."
+    try:
+        example = importlib.import_module(f"{prefix}{example_name}")
+    except ImportError as exc:
+        raise ImportError("Could not find example") from exc
+    example.main()
+
+
+def shell_is_interactive():
+    """
+    Returns True if the shell is interactive and False otherwise.
+    """
+    try:
+        return isinstance(get_ipython(), InteractiveShell)
+    except ImportError:
+        return False

examples/anim_gravity.py

@@ -0,0 +1,76 @@
+"""
+Example for animating a gravity simulation.
+"""
+
+import argparse
+import numpy as np
+
+# #BOOKLISTSTART# #
+import matplotlib.pyplot as plt
+from matplotlib import animation
+from amuse.io import read_set_from_file
+from amuse.units import units
+
+
+def animate(x, y):
+
+    def update(i):
+        data = np.stack([x[i], y[i]]).T
+        scat.set_offsets(data)
+
+        return (scat,)
+
+    number_of_snaps = len(x)
+    fig = plt.figure(figsize=(8, 8))
+    ax = fig.add_subplot(1, 1, 1)
+    ax.set_xlim((-1.2, 1.2))
+    ax.set_ylim((-1.2, 1.2))
+    ax.set_xlabel("X [au]")
+    ax.set_ylabel("Y [au]")
+
+    colormap = ["#FFFF00", "wheat", "deepskyblue"]
+    size = [40, 20, 20]
+    edgecolor = ["orange", "wheat", "deepskyblue"]
+
+    ax.set_facecolor("black")
+    scat = ax.scatter(x[0], y[0], c=colormap, s=size, edgecolor=edgecolor)
+    anim = animation.FuncAnimation(fig, update, frames=number_of_snaps, interval=30)
+    anim.save("anim_gravity.mp4", dpi=150, writer=animation.FFMpegWriter(fps=25))
+
+
+# #BOOKLISTSTOP# #
+
+
+def anim_gravity(filename="sun_venus_earth.amuse", **kwargs):
+    particles = read_set_from_file(filename)
+
+    x = []
+    y = []
+    for si in particles.history:
+        x.append(si.x.value_in(units.au))
+        y.append(si.y.value_in(units.au))
+
+    animate(x, y)
+
+
+def new_argument_parser():
+    parser = argparse.ArgumentParser(
+        formatter_class=argparse.ArgumentDefaultsHelpFormatter
+    )
+    parser.add_argument(
+        "-i",
+        "--filename",
+        type=str,
+        default="sun_venus_earth.amuse",
+        help="input filename",
+    )
+    return parser
+
+
+def main(**kwargs):
+    anim_gravity(**kwargs)
+
+
+if __name__ == "__main__":
+    arguments = new_argument_parser().parse_args()
+    main(**arguments.__dict__)