Build a path for the camera

How to use the class Path

import cartopy.crs as ccrs
import cartopy.feature as cfeature
import matplotlib.pyplot as plt
import numpy as np
import xarray as xr

from anim.path import TimePath

ANIM_FPS = 60
ANIM_OUTPUT_FOLDER = "animation/example_20"

ANIM_MAX_FRAMES = ANIM_FPS * 10


def plot(i_image, ds):
    """créée une figure"""

    extent = ds.attrs["extent"]
    tn = ds.attrs["tn"]
    speed = ds.attrs["speed"]

    fig = plt.figure(figsize=(7, 3.5), dpi=80)

    ax = fig.add_subplot(1, 1, 1, projection=ccrs.PlateCarree())
    ax.set_extent(extent, crs=ccrs.PlateCarree())

    ax.coastlines()
    ax.add_feature(cfeature.LAND)
    ax.add_feature(cfeature.OCEAN)

    gl = ax.gridlines(draw_labels=True)
    gl.top_labels = False
    gl.right_labels = False

    x0, x1, y0, y1 = extent
    x = (x0 + x1) / 2
    y = (y0 + y1) / 2

    ax.set_title(f"i={i_image:03d} date={tn} | pos=({x:6.2f}, {y:6.2f}), speed={speed:6.2f}°/day", fontsize=11)

    return fig


def compute():
    t0 = np.datetime64("2003-06-03T00:25:00")

    # cannot have float when creating timedelta64, so use seconds
    dt = np.timedelta64(int(60 * 60 * 24 / ANIM_FPS), "s")

    path = TimePath(coords=(-5, 36), dx=20, dy=10, t0=t0)
    # move to the coordinate (9, 43) in 2 days
    path.move(np.timedelta64(2, "D"), coords=(9, 43))
    # move to the coordinate (15, 41) in 1 days
    path.move(np.timedelta64(1, "D"), coords=(15, 41))
    # move to the coordinate (26, 36) in 3 days and zoom in (=> reducing dx and dy by a half)
    path.move_and_zoom(np.timedelta64(3, "D"), zoom=2, coords=(26, 36))

    # wait a little (move to the same place in 1 day, so no move)
    path.move(np.timedelta64(1, "D"))

    # don't move, but change the zooming by dezooming until having dx=40 and dy=20
    path.move_and_focus(np.timedelta64(3, "D"), dx=40, dy=20)

    for tn, extent, speed in zip(*path.compute_path(dt)):
        ds = xr.Dataset(attrs={"tn": tn, "extent": extent, "speed": speed})
        yield ds