[graph-tool] Adding edge list from file too large to fit into memory
Tiago de Paula Peixoto
tiago at skewed.de
Mon Feb 1 19:20:57 CET 2021
Am 01.02.21 um 12:32 schrieb James Ruffle:
> Dear Graph-Tool community,
>
> I am trying to construct a graph with a large number of edges, using an
> np file as an edge_list.
> There are 125760 vertices and an edge list of length (7907725920, 2).
>
> In order to use the npy edge_list file, I have needed to load the edge
> list as a readable memmap because, at a size of 126Gb, it is far too
> large to load into memory. But, when calling add_edge_list to this
> memmap, I think it is still being loaded into memory as the RAM will
> fill and the python session crash. I suppose the alternative is that the
> graph object becomes too large to hold into memory, but with previous
> large graphs I did not find this to be the problem. Does anybody have a
> solution to this issue?
I'm not sure what kind of solution you are expecting. Do you want
Graph.add_edge_list() *not* to load the edges into memory?
> Lastly, after I find a means to add this number of edges, I need to
> assign weights to the edges, again from a memmap file due to its size,
> which gives me the same problem. Any advice?
>
>
> *Sample code:*
>
> #prime the graph with the number of vertices
> g = Graph(directed=False)
> g.add_vertex(125760)
>
> #load the edge list as memmap and add it
> idx_indi_mmap = np.load('idx_indi.npy', mmap_mode='r’)
> idx_indi_mmap.shape #(7907725920, 2)
>
> g.add_edge_list(idx_indi_mmap) #script will crash at this point from
> filling the RAM
>
> #Then want to add weights by taking the indices from another memmap object
> node_matrix = np.load('node_matrix.npy', mmap_mode='r’)
> node_matrix.shape #(125760, 125760)
> weights = node_matrix[idx_indi_mmap]
> ew = g("double")
> ew.a = weights
> g.ep[‘weight'] = ew
You might save some intermediary memory by loading the weights in one go
with Graph.add_edge_list() (see the 'eprops' parameter), which requires
a numpy array with three values, (source, target, weight).
However, if you do not have enough RAM to hold the entire graph +
weights into memory, this is also not going to work.
Best,
Tiago
--
Tiago de Paula Peixoto <tiago at skewed.de>
More information about the graph-tool
mailing list