Get all pairs from a 2D matrix in columns (CSV)

Given a matrix 3x4 like this one:

a = [ 12 34 25 23

76 12 8 59

23 56 89 61]

I would like to export it to a csv file like this (including the first 2 columns as row x column indexes from 2 other matrixes):

rows = [56 12 90]

columns = [4 2 8 1]

CSV:

56,4,12

56,2,34

56,8,25

56,1,23

12,4,76

..

I'm new to matlab, any ideas?

I have tried this:

A = A([1:3 1:end]);
A = permute(A,[2 1]);
csvwrite("test.csv",A);

Which works for matrix A, but I'm unable so far to put together the other 2 matrixes into columns 1, 2 as in the example above.

Thanks in advance,

Answer 1

[Jalaj Gambhir]

Hi,

This can be achieved as follows:

[m,n] = ndgrid(rows,columns);
row_col = [m(:),n(:)];

Here row_col results in:

row_col =

    56     4
    12     4
    90     4
    56     2
    12     2
    .      .
    .      .

Then, you can flatten your array 'a' row-wise using:

flat_array = reshape(a.',1,[]);

Finally, concatenate the 'row_col' and 'flat_array' horizontally.

final_result = horzcat(row_col, flat_array);

Result obtained:

56     4    12
12     4    34
90     4    25
56     2    23
12     2    76
.      .     .
.      .     .