Collapsing preallocated memory of sparse matrix
显示 更早的评论
I used sparse matrix for some calculation, and I roughly know how many nnz will be stored. So I preallocated a slightly larger memory when I initialize that sparse matrix.
reserveRate = 1.2 % 120%
A = spalloc(n,m,estimated_nnz * reserveRate);
After finishing the calculation, since the memory has some unfilled margin, I would like to remove those space. Is there any way to do so?
采纳的回答
Bjorn Gustavsson
2019-1-22
0 个投票
Is there a particular reason you dont collect the non-zero values and their matrix indices into 3 arrays and then after all those are completed first then generating the sparse array? That is the general advice to not over-allocate.
HTH
2 个评论
Hyeokjin Jho
2019-1-23
Bjorn Gustavsson
2019-1-23
But if your arrays with the non-zero values and the corresponding row and column indices take up over 50% of your memory wouldn't you rapidly run into problems as soon as you start doing operations on the sparse array?
Sad follow-up suggestion: read the indices first, then you candetermine the exact size needed so you can allocate the minimal A, and then do another read to fill it? If it is so that you just get the values and indices in some calculation maybe another way would be to store them in arrays, save to file(s) - then you might be able to wiggle your way around by determining the size of A and then populate it. I know these are "not pretty" suggestions...
更多回答（0 个）
类别
在 帮助中心 和 File Exchange 中查找有关 Sparse Matrices 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!
Translated by 
