[R] How to change the number of axis?

[qiao xue]

Hi,

I use R to plot a graph with 20000 frames. Because the limit of pixel
or others, the screen fail to show the graph. So I have to draw a
point every 10 frames. So the total of x axis becomes 2000.
So when imaging the picture, I still hope that the total of x-axis is
20000.  I need to find a way to modify the number of axis.
How could I do this?

Thanks!