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

[Benjamin R. <ben...@ou...>]

On Wed, Oct 6, 2010 at 1:06 PM, Michael Cracraft <mic...@gm...
> wrote:

> 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
>
>
Michael,

Which version of matplotlib are you using?  Which backend are you using?
Also, could you include a small script or two that demonstrate the problem?
This way, we can poke around with it and see what is up.

Ben Root