how do I merge multiple matrices into one?

I have 50 1111 x 3 size matrics. I want to combine them into one final matrix such as all first rows from individual matrices are in first 50 rows and then all 2nd rows and so on. Also, for each set of rows it should insert a header row at the beginning.

How do I do this in Matlab?

[James Tursa]

How are these 50 variables stored in MATLAB currently? As separately named variables? How do you get them into the workspace?

[Shirish Kulkarni]

each of 50 matrix has 1111 rows and 3 columns. They are stored seperately with unique name.

[Bob Thompson]

How are you creating the variables?

The only 'good' way of combining 50 unique variables (as far as I know) is manually, but it might be possible to index the results when you first make them so they don't need to be individual variables.

[Walter Roberson]

Is this for writing into an xlsx file? SInce you cannot create a numeric array that has header rows in the middle of it, and if you were to create a table() object all of the entries would have to be cells in order to permit the header rows to be in middle of it.

[Shirish Kulkarni]

I have the header rows (numerical values) in another seperate matrix that I want to insert in resultant matrix.

Answer 1

[Walter Roberson]

One approach

N = 4;     %50 in your original
Rows = 2;  %1111 in your original

%generate some data for illustration
M = arrayfun(@(ignore) randi(9,Rows,3), (1:N).', 'uniform', 0)

M = 4x1 cell array
    {2×3 double}
    {2×3 double}
    {2×3 double}
    {2×3 double}

cell2mat(M)   %for illustration

ans = 8×3

1 3 7 1 6 7 6 1 8 4 9 5 9 8 3 4 6 9 4 8 8 3 7 6

nrow = size(M{1},1);
headers = repmat(-(1:nrow).', 1, 3);
grouped = arrayfun(@(row) cell2mat(cellfun(@(C) C(row,:), M, 'uniform', 0)), 1:nrow, 'uniform', 0)

grouped = 1x2 cell array
    {4×3 double}    {4×3 double}

headered = [num2cell(headers,2).'; grouped]

headered = 2x2 cell array
    {1×3 double}    {1×3 double}
    {4×3 double}    {4×3 double}

joint = cell2mat(headered(:))

joint = 10×3

-1 -1 -1 1 3 7 6 1 8 9 8 3 4 8 8 -2 -2 -2 1 6 7 4 9 5 4 6 9 3 7 6