How to create Animations

Section author: Florian Zill (Helmholtz Centre for Environmental Research GmbH - UFZ)

To demonstrate the creation of an animated plot we use a component transport example from the ogs benchmark gallery (https://www.opengeosys.org/docs/benchmarks/hydro-component/elder/).

import matplotlib.pyplot as plt
import numpy as np

import ogstools as ogs
from ogstools import examples

mesh_series = examples.load_meshseries_CT_2D_XDMF()

To read your own data as a mesh series you can do:

from ogstools.meshlib import MeshSeries
mesh_series = MeshSeries("filepath/filename_pvd_or_xdmf")

You can also use a variable from the available presets instead of needing to create your own: Variable presets and data transformation

Let’s use fixed scale limits to prevent rescaling during the animation.

ogs.plot.setup.vmin = 0
ogs.plot.setup.vmax = 100
ogs.plot.setup.dpi = 50

You can choose which timesteps to render by passing either an int array corresponding to the indices, or a float array corresponding to the timevalues to render. If a requested timevalue is not part of the timeseries it will be interpolated. In this case every second frame will be interpolated.

timevalues = np.linspace(
    mesh_series.timevalues()[0], mesh_series.timevalues()[-1], num=25
)

Now, let’s animate the saturation solution. A timescale at the top indicates existing timesteps and the position of the current timevalue. Note that rendering many frames in conjunction with large meshes might take a really long time. We can pass two functions to animate: mesh_func which transforms the mesh and plot_func which can apply custom formatting and / or plotting.

def mesh_func(mesh: ogs.Mesh) -> ogs.Mesh:
    "Clip the left half of the mesh."
    return mesh.clip("-x", [0, 0, 0])


def plot_func(ax: plt.Axes, timevalue: float) -> None:
    "Add the time to the title."
    ax.set_title(f"{timevalue/(365.25*86400):.1f} yrs", loc="center")

anim = mesh_series.animate(
    ogs.variables.saturation,
    timevalues,
    mesh_func=mesh_func,
    plot_func=plot_func,
)

Once Loop Reflect

 0%|          | 0/25 [00:00<?, ?it/s]
 4%|▍         | 1/25 [00:00<00:03,  6.30it/s]
 8%|▊         | 2/25 [00:00<00:03,  6.35it/s]
12%|█▏        | 3/25 [00:00<00:03,  6.71it/s]
16%|█▌        | 4/25 [00:00<00:03,  6.58it/s]
20%|██        | 5/25 [00:00<00:02,  6.78it/s]
24%|██▍       | 6/25 [00:00<00:02,  6.63it/s]
28%|██▊       | 7/25 [00:01<00:02,  6.79it/s]
32%|███▏      | 8/25 [00:01<00:02,  6.65it/s]
36%|███▌      | 9/25 [00:01<00:02,  6.80it/s]
40%|████      | 10/25 [00:01<00:02,  6.65it/s]
44%|████▍     | 11/25 [00:01<00:02,  6.80it/s]
48%|████▊     | 12/25 [00:01<00:01,  6.65it/s]
52%|█████▏    | 13/25 [00:01<00:01,  6.79it/s]
56%|█████▌    | 14/25 [00:02<00:01,  6.61it/s]
60%|██████    | 15/25 [00:02<00:01,  6.76it/s]
64%|██████▍   | 16/25 [00:02<00:01,  6.62it/s]
68%|██████▊   | 17/25 [00:02<00:01,  6.76it/s]
72%|███████▏  | 18/25 [00:02<00:01,  6.62it/s]
76%|███████▌  | 19/25 [00:02<00:00,  6.75it/s]
80%|████████  | 20/25 [00:03<00:00,  5.27it/s]
84%|████████▍ | 21/25 [00:03<00:00,  5.69it/s]
88%|████████▊ | 22/25 [00:03<00:00,  5.85it/s]
92%|█████████▏| 23/25 [00:03<00:00,  6.16it/s]
96%|█████████▌| 24/25 [00:03<00:00,  6.20it/s]
96%|█████████▌| 24/25 [00:03<00:00,  6.20it/s]

The animation can be saved (as mp4) like so:

ogs.plot.utils.save_animation(anim, "Saturation", fps=5)