Read sparse matrix from notepad

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Mark Sc
Mark Sc il 18 Gen 2022
Commentato: James Tursa il 20 Gen 2022
Hi all,
I am trying to read a sparse matrix from a notepad.. I tried with the following matrix however, it's not given the correct sparse matrix:
clear all
clc
M=readmatrix('S_sp.dat');
I would like to the output to be as:
(1,1) 5.7744185
(1,2) 0.00
and so on...
I understand sprase should be without zero, but I need to read the file as it is , and be in a sparse format
I already attached the file in a zip folder
  2 Commenti
James Tursa
James Tursa il 18 Gen 2022
Modificato: James Tursa il 18 Gen 2022
Can you provide a small sample of numbers in a txt or mat file instead of a zip file? Also, the sparse format in MATLAB does not store 0's. Trying to create such a matrix, even using hacks, would only result in an invalid sparse matrix and would violate assumptions made in background sparse matrix operations. Why do you think you need to physically store 0's in your sparse matrix?
Normally one would read in the data and then generate the sparse matrix from this data, which unfortunately results in two copies of the data in memory. The only ways I know of to read data directly into a sparse matrix would be to use a mex routine or to have the data in a mat file (e.g., text version) already in sparse format. Is the size of the matrix and the number of elements known prior to reading the elements?
Mark Sc
Mark Sc il 18 Gen 2022
@James Tursa Thank you so much for your comment,
I upload in .txt
The data in the file already sparse, I need to write it same, but with same format of sparse in matlab so I could use it later,
Hope you could help me...
Thank you,

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Matt J
Matt J il 18 Gen 2022
S=spconvert(load('S_sp.txt'))
  5 Commenti
Mark Sc
Mark Sc il 19 Gen 2022
@Matt J and @James Tursa Thank you both so much
James Tursa
James Tursa il 20 Gen 2022
Note that these methods still have two copies of the data in memory, but as stated previously this probably can't be avoided in your case unless you resort to a mex routine.

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