Hi, I'm using graph tool to represent a mesh of apical junctions (interconnected cells in a tissue). As my simulation goes, positions of the graph nodes change. Positions are stored as 3 vertex property maps with type <double> (i.e. x, y and z). For now, I write a graphxml file (plus possibliy a .png image of the graph) each time I change the nodes positions. I would like to store the history of each node position, in other terms its trajectory, but I feel that doing so by assigning a property map with type vector<double> to each node would produce big files: I typically have about 5000 vertices, and up to 350 'time points'. I would also need to store other propery maps (describing each vertex and edge state in the simulation). A full static view right now gives a 24 Mb xml file... The point is I usually only need the static version, which I tend to open and close quite often, and that allready takes quite some time to open. So I thought I could for exemple store the graph's history in a separate h5 file and access only if needed, for exemple, and only store a reference to the file in the graph. I'd really apreciate to have some insight into that before I go on coding... Cheers, Guillaume