iterator based plot

[toton]

Hi,
for my project I needs a few plots to visualize the data (mostly x-y
plot) . Most of the existing plotting library either copy the data and
do plotting, or takes a data pointer to an 2d x-y array, and plots it
(without copying). As my data set is not so trivial (sometimes it is
vector, sometimes list etc), and x, y are not fixed. so I want to have
a plot as generic one, which take begin & end iterator, iterate over it
and show the result.
Thus, say I have data in the form vector<Point> , and where
class Point{
int x;
int y;
int z;
int i;
};
and have ctor, and getters.
Now, I want to specify, two iterators for the vector (or any other
thing which can give two iterators, one of the forward iterator, or
reverse iterator is a minimum condition), and also what to plot. I dont
want to hardcode it saying Point "need to have" some x() and y() .
Rather than I want to say, use x() and y() or y() and i() as data. Some
sort of casting wil be fine.

Anyone can give an idea? or point to a link for it (or already existing
open-source library) ?
I NO-NOT need the graphics code, or how to implement the plot . I am
looking for how to interface data to plot.

Any help appreciated.
Thanks
abir