scitools.MovingPlotWindow

Manage a moving plot window for displaying very long time series.

class scitools.MovingPlotWindow.MovingPlotWindow(window_width, dt, yaxis=[-1, 1], mode='continuous movement', pause=1.5)

Make a plot window that follows the tip (end) of a very long time series.

Example:

def demo(I, k, dt, T, mode='continuous movement'):
    """
    Solve u' = -k**2*u, u(0)=I, u'(0)=0 by a finite difference
    method with time steps dt, from t=0 to t=T.
    """
    if dt > 2./k:
        print 'Unstable scheme'
    N = int(round(T/float(dt)))
    u = zeros(N+1)
    t = linspace(0, T, N+1)

    umin = -1.2*I
    umax = -umin
    period = 2*pi/k  # period of the oscillations
    window_width =
    plot_manager = MovingPlotWindow(
                     window_width, dt, yaxis=[umin, umax],
                     mode=mode)
    u[0] = I
    u[1] = u[0] - 0.5*dt**2*k**2*u[0]
    for n in range(1,N):
        u[n+1] = 2*u[n] - u[n-1] - dt**2*k**2*u[n]

        if plot_manager.plot(n):
            s = plot_manager.first_index_in_plot
            plot(t[s:n+2], u[s:n+2], 'r-',
                 t[s:n+2], I*cos(k*t)[s:n+2], 'b-',
                 axis=plot_manager.axis(),
                 title="Solution of u'' + k^2 u = 0 for t=%6.3f (mode: %s)" % (t[n+1], mode))
        plot_manager.update(n)

Methods

axis()	Return the axis limits as a list [xmin, xmax, ymin, ymax].
plot(n)	Return True if a plot is to be drawn at time step number n,
update(n)	Update the plot manager (MovingPlotWindow) at time step n.

__init__(window_width, dt, yaxis=[-1, 1], mode='continuous movement', pause=1.5)

Argument	Description
window_width	tmax-tmin in a plot window
dt	time step (constant)
yaxis	extent of y axis
mode	method for moving the plot window, see below.

The mode parameter has three values:

• 'continuous movement': the plot window moves one time step for each plot.
• 'continuous drawing': the curves are drawn from left to right, one step at a time, and plot window jumps when the curve reaches the end.
• 'jumps': the curves are shown in a window for a time equal to the pause argument, then the axis jumps to a new time window of the same length

See also the test block of the module for testing out the three different modes of this class.

__module__ = 'scitools.MovingPlotWindow'

axis()

Return the axis limits as a list [xmin, xmax, ymin, ymax].

plot(n)

Return True if a plot is to be drawn at time step number n, otherwise return False.

update(n)

Update the plot manager (MovingPlotWindow) at time step n.