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?
#prime the graph with the number of vertices
g = Graph(directed=False)
#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.
Tiago de Paula Peixoto <tiago(a)skewed.de>