{ I think this message got rejected at the 1st attempt - trying again}

R 2.15.1 , windows XP

I have a  very non-stationary  bivariate  time-series - say  {xt,yt}  t=1 ... lots.

I want to do a bivariate density contour-plot of the whole series and then  step
through the series 1 second at a time plotting that second's  {x,y} subset on top of the contour
plot and losing the previous second's subset so that the effect enables you to see
an 'animation' of how the series 'travels' through  different parts of the joint density  as time passes.

The only way I've found to do this is to repeatedly call contour() before plotting  each
seconds-worth of data ... this works, but because of the time taken to do the  contour()
calculations in each step of the loop , it has an unpleasant flashing appearance.

Is it possible to run contour() just once and save the contour- plotting info, so that in each
step of the loop I only have do the actual plotting of the contours?

Or any other way of achieving the desired outcome.

Grateful for any guidance      ...     Bob Kinley

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