[Matplotlib-users] Issue with Redrawing a Line (numpy.ndarray, set_ydata, and draw)

[Michael C. <mic...@gm...>]

I have a code that continuously modifies a numpy.ndarray variable.  Then, I
use set_ydata on the matplotlib.lines.Line2D object to the same ndarray
variable.  Then, I call fig.canvas.draw() to redraw the figure, where fig is
Figure object.

However, the line on the graph never changes.  I print a few entries to the
console to make sure that the variable is changing.

It seems like the only way I can get the line to update is to create a
completely new ndarray, update that variable with the new values and use
set_ydata on my line object.  Then, the redraw works.  Other things that I
tried that didn't seem to work were:

L1.set_ydata(x[:])
L1.set_ydata(x.tolist())
L1.set_ydata(list(x))


where L1 is my line object, and x is my ndarray.  To make it redraw I have
to do something like this.

xnew = numpy.zeros(numpy.size(x,0))
for k in range(numpy.size(x,0)):
     xnew[k] = x[k]
L1.set_ydata(xnew)
fig.canvas.draw()

Is there some switch I can set to force a redraw of the elements?  I feel
like I am missing something fundamental.

Thanks,
Michael

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