Added movie creation code for KH instability

examples/KelvinHelmholtz_2D/makeMovie.py

+"""
+Makes a movie of the KH 2D data.
+
+You will need to run your movie with far higher time-resolution than usual to
+get a nice movie; around 450 snapshots over 6s is required.
+
+Edit this file near the bottom with the number of snaps you have.
+
+Written by Josh Borrow (joshua.borrow@durham.ac.uk)
+"""
+
+import matplotlib
+matplotlib.use("Agg")
+
+import os
+import h5py as h5
+import numpy as np
+import scipy as sp
+import scipy.interpolate as si
+import matplotlib.pyplot as plt
+
+
+def load_and_extract(filename):
+    """
+    Load the data and extract relevant info.
+    """
+
+    with h5.File(filename, "r") as f:
+        x, y, _ = f["PartType0/Coordinates"][...].T
+        density = f["PartType0/Density"][...]
+
+    return x, y, density
+
+
+def make_plot(filename, array, nx, ny, dx, dy):
+    """
+    Load the data and plop it on the grid using nearest
+    neighbour searching for finding the 'correct' value of
+    the density.
+    """
+
+    data_x, data_y, density = load_and_extract(filename)
+
+    # Make the grid
+    x = np.linspace(*dx, nx)
+    y = np.linspace(*dy, ny)
+
+    xv, yv = np.meshgrid(x, y)
+
+    mesh = si.griddata((data_x, data_y), density, (xv, yv), method="nearest")
+
+    array.set_array(mesh)
+
+    return array,
+
+
+def frame(n, *args):
+    """
+    Make a single frame. Requires the global variables plot and dpi.
+    """
+
+    global plot, dpi
+
+    fn = "{}_{:04d}.hdf5".format(filename, n)
+
+    return make_plot(fn, plot, dpi, dpi, (0, 1), (0, 1))
+
+
+if __name__ == "__main__":
+    from tqdm import tqdm
+    from matplotlib.animation import FuncAnimation
+    from scipy.stats import gaussian_kde
+
+    filename = "kelvinhelmholtz"
+    dpi = 512
+
+    frames = tqdm(np.arange(0, 448))
+
+    # Creation of first frame
+    fig, ax = plt.subplots(1, 1, figsize=(1, 1), frameon=False)
+
+    data_x, data_y, density = load_and_extract("kelvinhelmholtz_0000.hdf5")
+
+    x = np.linspace(0, 1, dpi)
+    y = np.linspace(0, 1, dpi)
+    xv, yv = np.meshgrid(x, y)
+
+    mesh = si.griddata((data_x, data_y), density, (xv, yv), method="nearest")
+    
+    # Global variable for set_array
+    plot = ax.imshow(mesh, extent=[0, 1, 0, 1], animated=True, interpolation="none")
+
+    anim = FuncAnimation(fig, frame, frames, interval=40, blit=False)
+
+    # Remove all whitespace
+    fig.subplots_adjust(left=0, bottom=0, right=1, top=1, wspace=None, hspace=None)
+
+    # Actually make the movie
+    anim.save("khmovie.mp4", dpi=dpi, bitrate=4096)