Animate movement vectors — animate_movement

animate_movement_vectors() produces a gganim object in which each frame is a map of vectors showing the average modeled movement for all birds from each cell in the landscape at a given timestep. It is analogous to a series of images created with plot_movement_vectors().

Usage

animate_movement_vectors(bf, ...)

Arguments

bf

A BirdFlow object

...

Arguments passed on to lookup_timestep_sequence

season: a season name, season alias, or "all". See lookup_season_timesteps() for options.
start: The starting point in time specified as a timestep, character date, or date object.
end: The ending point in time as a date or timestep.
direction: Either "forward" or "backward" defaults to "forward" if not processing dates. If using date input direction is optional and is only used to verify the direction implicit in the dates.
season_buffer: Only used with season input. season_buffer is passed to lookup_season_timesteps() and defaults to 1; it is the number of timesteps to extend the season by at each end.
n_steps: Alternative to end The end will be n_steps away from start in direction; and the resulting sequence will have n_step transitions and n_steps + 1 timesteps.

Value

A gganim object. print() will plot it with default options, or use animate() to set the options. See the example for recommended settings.

Details

Each arrow represents the average of all the transitions from a single cell. The tail of the arrow is the center of that cell, the head is the average location at the following timestep for birds that start at that cell.

The timestep and/or date label is the starting timestep for the transition that is displayed and the format depends on birdflow_options("time_format")

Thicker lines and less transparency (darker shading) indicate higher density in the eBird S&T distribution for the beginning timestep of the displayed transition.

Use the "ragg_png" device when rendering animations as in the example code.

Examples


bf <- BirdFlowModels::amewoo
a <- animate_movement_vectors(bf)
#> Creating vector fields
#> 	....................................................

if (FALSE) { # \dontrun{

# Animate, display, and save
#   Note: "ragg_png" is considerably faster and produces cleaner output than
#         the default device.
gif <- gganimate::animate(a, fps = 1, device = "ragg_png",
                          width = 6, height = 5,
                          res = 150, units = "in")
print(gif)

# Save
gif_file <- tempfile("animation", fileext = ".gif")
gganimate::save_animation(gif, gif_file)
file.remove(gif_file) # cleanup
} # }