XY graph manipulation

[guillaume trager]

I am plotting an XY graph (X for time and Y for an amplitude). As i
plot this graph the whole set of points are presented.
I wish i could present the graph, reducing the X axis width(10 seconds
width) and iterate to plot 10 sec to 10 sec(segments of 10 seconds).
one problem is time values are not spaced uniformaly.
could do give me some hints?
thank you,