Re: [Matplotlib-users] Lorenz -- another Q

[Sterling S. <sm...@fu...>]

Prahas,

If I read it correctly, it looks like all of your x,y,z values are stored in x_t (and computed before plotting).  See http://docs.scipy.org/doc/numpy/reference/generated/numpy.savetxt.html
to output these to a file, if so desired.

-Sterling

On Mar 11, 2015, at 8:07AM, Prahas David Nafissian <pra...@gm...> wrote:

> Hi,
> 
> Given the Lorenz code shared yesterday, is there a way
> to generate a log file of the x,y,z points generated?
> 
> Thanks in advance.
> 
> --Prahas
> 
> In case you deleted the code:
> 
> 
> import numpy as np
> from scipy import integrate
> 
> from matplotlib import pyplot as plt
> from mpl_toolkits.mplot3d import Axes3D
> from matplotlib.colors import cnames
> from matplotlib import animation
> 
> # orig value of N_traj was 20 -- very cool this way.
> 
> N_trajectories = 1
> 
> def lorentz_deriv((x, y, z), t0, sigma=10., beta=8./3, rho=28.0):
>    """Compute the time-derivative of a Lorentz system."""
>    return [sigma * (y - x), x * (rho - z) - y, x * y - beta * z]
> 
> # Choose random starting points, uniformly distributed from -15 to 15
> 
> np.random.seed(1)
> 
> # changing from -15,30 to 10,5 below starts the drawing in the middle,
> # rather than getting the long line from below....
> # if using N_Traj > 1, return to orig values.
> 
> # x0 = -15 + 30 * np.random.random((N_trajectories, 3))
> 
> x0 = 10 + 5 * np.random.random((N_trajectories, 3))
> 
> 
> # Solve for the trajectories
> 
> # orig values:  0,4,1000
> # 3rd value -- lower it, it gets choppier.
> # 2nd value -- increase it -- more points, but speedier.
> 
> # change middle num from 4 to 15 -- this adds points!!!!!!!!
> 
> t = np.linspace(0, 40, 3000)
> x_t = np.asarray([integrate.odeint(lorentz_deriv, x0i, t)
>                  for x0i in x0])
> 
> # Set up figure & 3D axis for animation
> fig = plt.figure()
> ax = fig.add_axes([0, 0, 1, 1], projection='3d')
> 
> # changing off to on below adds axises.  slows it down but you
> # can fix that with interval value in the animation call
> 
> ax.axis('on')
> 
> # choose a different color for each trajectory
> colors = plt.cm.jet(np.linspace(0, 1, N_trajectories))
> 
> # set up lines and points -- this is a correction from
> # the orig jake code.  the next four lines...
> 
> lines = [ax.plot([], [], [], '-', c=c)[0]
> for c in colors]
> pts = [ax.plot([], [], [], 'o', c=c)[0]
> for c in colors]
> 
> # prepare the axes limits
> ax.set_xlim((-25, 25))
> ax.set_ylim((-35, 35))
> ax.set_zlim((5, 55))
> 
> # set point-of-view: specified by (altitude degrees, azimuth degrees)
> ax.view_init(30, 0)
> 
> # initialization function: plot the background of each frame
> def init():
>    for line, pt in zip(lines, pts):
>        line.set_data([], [])
>        line.set_3d_properties([])
> 
>        pt.set_data([], [])
>        pt.set_3d_properties([])
>    return lines + pts
> 
> # animation function.  This will be called sequentially with the frame number
> def animate(i):
>    # we'll step two time-steps per frame.  This leads to nice results.
> 
>    i = (2 * i) % x_t.shape[1]
> 
>    for line, pt, xi in zip(lines, pts, x_t):
>        x, y, z = xi[:i].T
>        line.set_data(x, y)
>        line.set_3d_properties(z)
> 
>        pt.set_data(x[-1:], y[-1:])
>        pt.set_3d_properties(z[-1:])
> 
>        # changed 0.3 to 0.05 below -- this slows the rotation of the view.
>        # changed 30 to 20 below
>        # changing 20 to (20 + (.1 * i)) rotates on the Z axis.  trippy.
> 
>    ax.view_init(10, 0.1 * i)
>    # ax.view_init(10, 100)
>    fig.canvas.draw()
>    return lines + pts
> 
> # instantiate the animator.  I've deleted the blit switch (for Mac)
> # enlarging frames=500 works now -- it failed before because I didn't give it
> # enough data -- by changing the t=np.linspace line above I generate
> more points.
> # interval larger slows it down
> # changed inteval from 30 to 200, frames from 500 to 3000
> 
> anim = animation.FuncAnimation(fig, animate, init_func=init,
>                               frames=3000, interval=200)
> 
> # Save as mp4. This requires mplayer or ffmpeg to be installed. COMPLEX!!!!!
> # Instead, use a screen record program:  Quicktime on the Mac; MS
> Expression Encoder on PC.
> # anim.save('PDNlorentz_attractor.mp4', fps=15, extra_args=['-vcodec',
> 'libx264'])
> 
> plt.show()
> 
> ------------------------------------------------------------------------------
> Dive into the World of Parallel Programming The Go Parallel Website, sponsored
> by Intel and developed in partnership with Slashdot Media, is your hub for all
> things parallel software development, from weekly thought leadership blogs to
> news, videos, case studies, tutorials and more. Take a look and join the 
> conversation now. http://goparallel.sourceforge.net/
> _______________________________________________
> Matplotlib-users mailing list
> Mat...@li...
> https://lists.sourceforge.net/lists/listinfo/matplotlib-users