Creating sparse arrays seems exceptionally slow.
I can set up the non-zero data of the array relatively quickly. For
example, the following code takes about 80 seconds on one machine.
vec_len = 700000
row_ind = Uint64[]
col_ind = Uint64[]
value = Float64[]
for j = 1:700000
for k = 1:700
ind = k*50
push!(row_ind, ind)
push!(col_ind, j)
push!(value, 5.0)
end
end
but then
a = sparse(row_ind, col_ind, value, 700000, 700000)
takes more than at least about 30 minutes. (I never let it finish.)
It doesn't seem like the numbers I'm using should be that far off the
scale. Is there a more efficient way I should be doing what I'm doing? Am
I missing something and asking for something that really is impractical?
If not, I may be able to look into the sparse matrix code a little this
weekend.
The never-finishing result is the same if I try
sprand(700000, 700000, .001)
or if I try to set 700000*700 values in a sparse matrix of zeros directly.
Thanks.
