Re: [petsc-users] Union of sequential vecs

[Blaise Bourdin]

Hi, If you use an IS to store your ints, you can also do ISAllGather followed by ISSortRemoveDups Blaise On Dec 9, 2022, at 4:14 PM, Barry Smith <bsm...@petsc.dev> wrote:   Ok, so you want the unique list of integers sorted from all the seq vectors on ever MPI rank?    VecScatterCreateToAll() to get all values on all ranks (make the sequential vectors MPI vectors instead).     create an integer array long enough to hold all of them     Use VecGetArray() and a for loop to copy all the values to the integer array,     Use PetscSortRemoveDupsInt on the integer array   Now each rank has all the desired values. On Dec 9, 2022, at 3:24 PM, Karthikeyan Chockalingam - STFC UKRI <karthikeyan.chockalin...@stfc.ac.uk> wrote: That is where I am stuck, I don’t know who to combine them to get Vec = {2,5,7,8,10,11,12}. I just want them in an MPI vector.   I finally plan to call VecScatterCreateToAll so that all processor gets a copy.   Thank you.   Kind regards, Karthik.   From: Barry Smith <bsm...@petsc.dev> Date: Friday, 9 December 2022 at 20:04 To: Chockalingam, Karthikeyan (STFC,DL,HC) <karthikeyan.chockalin...@stfc.ac.uk> Cc: petsc-users@mcs.anl.gov <petsc-users@mcs.anl.gov> Subject: Re: [petsc-users] Union of sequential vecs     How are you combining them to get Vec = {2,5,7,8,10,11,12}?     Do you want the values to remain on the same MPI rank as before, just in an MPI vector?     On Dec 9, 2022, at 2:28 PM, Karthikeyan Chockalingam - STFC UKRI via petsc-users <petsc-users@mcs.anl.gov> wrote:   Hi,   I want to take the union of a set of sequential vectors, each living in a different processor.   Say,  Vec_Seq1 = {2,5,7} Vec_Seq2 = {5,8,10,11} Vec_Seq3 = {5,2,12}.   Finally, get the union of all them Vec = {2,5,7,8,10,11,12}.   I initially wanted to create a parallel vector and insert the (sequential vector) values but I do not know, to which index to insert the values to. But I do know the total size of Vec (which in this case is 7).   Any help is much appreciated.   Kind regards, Karthik.       This email and any attachments are intended solely for the use of the named recipients. If you are not the intended recipient you must not use, disclose, copy or distribute this email or any of its attachments and should notify the sender immediately and delete this email from your system. UK Research and Innovation (UKRI) has taken every reasonable precaution to minimise risk of this email or any attachments containing viruses or malware but the recipient should carry out its own virus and malware checks before opening the attachments. UKRI does not accept any liability for any losses or damages which the recipient may sustain due to presence of any viruses.  —  Canada Research Chair in Mathematical and Computational Aspects of Solid Mechanics (Tier 1) Professor, Department of Mathematics & Statistics Hamilton Hall room 409A, McMaster University 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada  https://www.math.mcmaster.ca/bourdin | +1 (905) 525 9140 ext. 27243