Actually it's https://github.com/JuliaLang/julia/pull/14798
On Wednesday, February 24, 2016 at 6:23:14 AM UTC-8, Kristoffer Carlsson wrote: > > https://github.com/JuliaLang/julia/pull/12608 > > On Wednesday, February 24, 2016 at 3:21:59 PM UTC+1, Christoph Ortner > wrote: >> >> Can you post a link to that pull request? >> Thanks, Christoph >> >> On Wednesday, 24 February 2016 04:26:35 UTC, Tony Kelman wrote: >>> >>> It is possible to store explicit zero values in sparse matrices, but not >>> via the sparse() function at the moment. You currently have to construct a >>> sparse matrix with the desired structure of stored elements, then modify >>> the field values of Mat.nzval to explicitly set some of them to zero. >>> There's an open pull request that will change this, I think the only thing >>> we were waiting for before merging was some performance benchmarking of >>> packages that heavily utilize the sparse() function. >>> >>> >>> On Tuesday, February 23, 2016 at 2:58:44 PM UTC-8, Yankai Cao wrote: >>>> >>>> Hi, Stefan, >>>> >>>> Thanks for your reply. For my application, the structure of the matrix >>>> is fixed, but the values of some elements might become zero from iteration >>>> to iteration. Is it possible to keep the position of elements whose values >>>> is zero? >>>> For example: >>>> I=[1;1;2] >>>> J=[1;1;2] >>>> V=[1.0;0.0;0.0] >>>> Mat=sparse(I,J,V,2,2) >>>> >>>> what I get is >>>> [1,1]=1 >>>> >>>> is it possible to get the following? >>>> [ 1, 1] = 1.0 >>>> [2, 2] = 0.0 >>>> >>>> >>>> Thanks. >>>> >>>> >>>> >>>> Yankai >>>> >>>> >>>> >>>> On Tuesday, February 23, 2016 at 4:50:07 PM UTC-6, Stefan Karpinski >>>> wrote: >>>>> >>>>> You can't have two values at the same row and column, which is what >>>>> the first two lines of this output would indicate: >>>>> >>>>> [1, 1] = 1.0 >>>>> [1, 1] = 1.0 >>>>> [2, 2] = 1.0 >>>>> >>>>> >>>>> Since the indices (1,1) appear twice the associated values are added, >>>>> giving 2.0. >>>>> >>>>> On Tue, Feb 23, 2016 at 5:03 PM, Yankai Cao <[email protected]> >>>>> wrote: >>>>> >>>>>> I am new to Julia. I have 2 questions about constructting sparse >>>>>> matrix from arrays. >>>>>> >>>>>> 1. >>>>>> I=[1;1;2] >>>>>> J=[1;1;2] >>>>>> V=[1.0;1.0;1.0] >>>>>> Mat=sparse(I,J,V,2,2) >>>>>> >>>>>> According to the Julia guide "If the combine function is not >>>>>> supplied, duplicates are added by default." I expect Mat to be >>>>>> [ 1, 1] =1.0 >>>>>> [ 1, 1] = 1.0 >>>>>> [2, 2] = 1.0 >>>>>> >>>>>> however, what I get is >>>>>> [1,1]=2 >>>>>> [2,2]=1 >>>>>> >>>>>> So what is the default behavior without combine function? How do I >>>>>> specify the combine function? There is no instructions about it right >>>>>> now. >>>>>> >>>>>> 2. when i change V=[1.0;0.0;0.0]. I expected >>>>>> [ 1, 1] = 1.0 >>>>>> [2, 2] = 0 >>>>>> >>>>>> what I get is >>>>>> [1,1]=1 >>>>>> >>>>>> How can I let julia to combine elements only according to the indexes >>>>>> I, J ? How to keep those elements with value 0 ? >>>>>> >>>>>> >>>>>> Thanks in advance. >>>>>> >>>>>> >>>>>> Yankai >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>
