Animate

last updated 09/06/2020

Animate

Animate is the class designed to allow systems to be plotted as animated figures, using matplotlib. While figures can be preiewed live, best results are obtained by saving as gifs or mp4s.

Methods

__init__(self,data,t,d=2, rows=1, columns=1):

data: Provides the coordinate data for the system, can be taken directly from the output of a SystemL object. This is a 2D numpy array

t: The times corresponding to the data - note that this is only used for basic purposes, and will not guarantee an accurate frame rate - this must be provided as an argument to the animator methods

d: The dimension of the figure, either 2 for 2d or 3 for 3d. If multiple figures are plotted a rowsxcolumns array of values may be provided to give different dimensions to each figure. A single value will be applied to all figures

rows: The number of rows of figures that should be plotted

columns: The number of columns of figures that should be plotted

returns: A reference to the Animate object

limits(self,x,y,z=False, row=1, column=1):

Sets the limits of the axes on a figure

x: A list of length 2 giving the minimum and maximum x coordinates to be plotted

y: A list of length 2 giving the minimum and maximum y coordinates to be plotted

z: A list of length 2 giving the minimum and maximum z coordinates to be plotted, or leave as False for a 2D figure

row: The row of the figure to which the limits are applied

column: The column of the figure to which the limits are applied

create_particle(self,a,conv, color = 'red', s=10, row=1, column=1):

Creates a Particle object within the Animate object that will be rendered on a figure. This appears as a point.

a: The initial location to place the particle, if creating an animation then data[0] is a suitable location as the first point the particle will exist at

conv: A function which takes in a list of the generalised coordinate data and returns a list or tuple of the coordinates that should be plotted on the figure

color: The color to draw the point - should be a recognised matplotlib color, including those from the xkcd color survey

s: The size to draw the particle

row: The row of the figure on which to plot the particle

column: The column of the figure on which to plot the particle

returns: A reference to the particle object for use when creating other graphical objects in the Animate object

create_rod(self,p1,p2, color=k, row=1, column=1):

Creates a Rod object within the nimate object that will be rendered on a figure. A rod is a straight connector between to particles and is drawns a line.

p1: A reference to a particle at one end of the rod

p2: A reference to a particle at the other end of the rod

color: The color to draw the rod - should be a recognised matplotlib color, including those from the xkcd color survey

row: The row of the figure on which to plot the rod

column: The column of the figure on which to plot the rod

create_spring(self,p1,p2,lamb,nat_l,color='red', row=1, column=1):

Creates a Spring object within the Animate object that will be rendered on a figure. A spring is a rod that changes color based on its length compared to a natural length and spring constant λ

p1: A reference to a particle at one end of the spring

p2: A reference to a particle at the other end of the spring

lamb: The spring constant of the spring material per unit length (=k/nat_l)

nat_l: The natural length of the spring

color: The color to draw the spring - should be a recognised matplotlib color, including those from the xkcd color survey

row: The row of the figure on which to plot the spring

column: The column of the figure on which to plot the spring

create_trace(self,p,length,color = None, row=1, column=1):

Creates a Trace object within the Animate object that will be rendered on a figure. The trace is a curve tracking the past locations of a particle.

p: A reference to the particle that will be traced

length: The number of frames for which to track the particle

color: The color of the trace, deafults to the color of the particle it is tracing

row: The row of the figure on which to plot the trace

column: The column of the figure on which to plot the trace

create_fade(self,p,length,color = None, row=1, column=1):

Creates a Fade object within the Animate object that will be rendered on a figure. The fade is a curve tracking the past locations of a particle, that fades out to transparency over time.

p: A reference to the particle that will be traced

length: The number of frames for which to track the particle

color: The color of the fade, deafults to the color of the particle it is tracing

row: The row of the figure on which to plot the fade

column: The column of the figure on which to plot the fade

create_polygon(self,ps,color='red',alpha=0.5, row=1, column=1):

Creates a Polygon object within the Animate object that will be rendered on a figure. The polygon is drawn with vertices at a series of particles, joining the first and last

ps: A list of references to the particles to be drawn around

color: The color of the polygon

alpha: The transparency of the polygon, an alpha value between 0 and 1

row: The row of the figure on which to plot the polygon

column: The column of the figure on which to plot the polygon

update(self,j):

Updates the locations of all the objects withi the animate object using the data array provided at creation.

j: The index at which to get the coordinate data from the data array provided

run(self, fps):

Run the animation live in a matplotlib window. This may be laggy on some computers - saving animations to file is strongly recommended for most purposes.

fps: The frames per second of the animation - for real time playback this should correspond to the frames per second of the data array

savegif(self, filename, fps):

Save the animation into an animated gif file. This method requires PIL to be installed.

filename: A string giving the filepath and filename, excluding the extension.

fps: The frames per second of the animation - for real time playback this should correspond to the frames per second of the data array

savemp4(self, filename, fps, ffmpeg_loc='C:/FFmpeg/bin/ffmpeg', dpi=500):

Save the animation into an mp4 file. This method requires ffmpeg to be installed.

filename: A string giving the filepath and filename, excluding the extension.

fps: The frames per second of the animation - for real time playback this should correspond to the frames per second of the data array

ffmpeg_loc: The location of the ffmpeg.exe file on the users computer e.g. default installation location of "C:/FFmpeg/bin/ffmpeg.exe" has ffmpeg_loc = 'C:/FFmpeg/bin/ffmpeg'

dpi: the dots per inch of the output mp4. Recommended for high quality is dpi=500.

Examples

Examples files can be found in the examples folder in the github repository

Animated Pendulum