Split table into Chunks.

Hi, I have a large table. I want to split the table into multiple chunks via loop and save its result in workspace so that later I can add into the powepoint slides in Matlab. But the subtables stores in .mat file. I want to save them into workspace as a table.

how can I do it. Any help would be great.

Thanks

I have written the following code:

T = T_measfine;
chunkSize = 8; % chunk size from number of rows
noOfChunks = ceil(size(T,1) / chunkSize)
% %%  To Output chunks
for idx = 1:noOfChunks
    if idx == noOfChunks
        subtable = T(1:end,:)
    else 
        subtable = T(1:chunkSize,:)
        savefile = strcat('subdata',num2str(idx));
        save(savefile, 'subtable')
    end
end

[Walter Roberson]

You want to create a table object whose variable contains rows, each of which is a table itself?

Or you want to dynamically create new variables in the workspace, each of which stores one of the subtables?

[Saria Ahmad]

I want to create new variables in the workspace.each of which stores one of the subtables.

I have multiple tables and I need to do this in a loop for every table.

[Walter Roberson]

Why do you need separate named variables? The process for adding information to PowerPoint slides involves calls that pass data by value not by variable name.

[Saria Ahmad]

the reason behind this: sometimes the resultant tables becomes very large and when I get the automated result file that large table doesn't fit to the slide. So Idea is to split the tables and then add them to slides.

[Walter Roberson]

yes but how does that require that different variables be used for each table? Instead of having a cell array of tables for example?

Answer 1

[Askic V]

Hello,

you're probably want something like this:

T = randi(10, 43,3);
chunkSize = 8; % chunk size from number of rows
noOfChunks = ceil(size(T,1) / chunkSize);

[rows, col] = size(T);
start_idx = 0;
for idx = 1:noOfChunks
     if idx == noOfChunks
         endpoint = rows; 
     else
         endpoint = start_idx + chunkSize; 
     end
     eval(sprintf('subTable%d = T(%d:endpoint,:)', idx, start_idx+1));
     start_idx  = chunkSize*idx;
end

subTable1 = 8×3

10 5 7 5 9 3 1 6 1 6 2 1 1 6 8 10 7 7 5 5 10 5 6 5

subTable2 = 8×3

2 2 2 5 9 2 5 10 6 3 6 1 4 2 8 6 9 10 3 6 6 3 2 10

subTable3 = 8×3

7 3 8 1 3 3 4 4 8 8 6 4 1 3 3 6 6 8 6 4 10 6 6 7

subTable4 = 8×3

7 7 9 8 3 6 10 8 10 6 10 5 7 1 6 10 5 2 9 1 9 9 9 10

subTable5 = 8×3

2 4 8 6 10 1 9 7 6 8 6 10 1 6 2 3 4 3 7 6 7 8 4 4

subTable6 = 3×3

5 9 6 6 5 3 10 8 7

If this is what you want, I need to warn you that this practice is highly unrecommended. YMATLAB arrays (for example cell) will let you do the same thing in a much faster, much more readable way.

[Saria Ahmad]

Thanks, Yes. This is what I want.

How can adapt in matlab arrays? Then I also have to adapt that subtables in power point slides via matlab. so then the problem arises.

[Stephen23]

"How can adapt in matlab arrays?"

By more slow, complex, inefficient, obfuscated code using the approach that you used to generate all of those variables. Bad data design forces you into writing bad code.

If you had sensibly used indexing as Askic V showed, then this would be simpler...

Answer 2

[Askic V]

I'm not really sure how you want to add subtables to power point slides, but you can create subtables in the following way:

T = randi(10, 53,3);
chunkSize = 8; % chunk size from number of rows
noOfChunks = ceil(size(T,1) / chunkSize);
rows = size(T,1);
cellArray = cell(0,3);

subTableNames = {};
for ii = 1:noOfChunks
    start_idx = (ii-1)*chunkSize+1;
    if ii == noOfChunks
        cellArray{ii} = T(start_idx:end, :); 
    else
        cellArray{ii} = T(start_idx:start_idx+chunkSize-1, :); 
    end
    subTableNames{ii} = ['T', num2str(ii)];
end

T2 = cell2table(cellArray(:).', 'VariableNames', subTableNames(:))

T2 = 1×7 table
         T1              T2              T3              T4              T5              T6              T7     
    ____________    ____________    ____________    ____________    ____________    ____________    ____________

    {8×3 double}    {8×3 double}    {8×3 double}    {8×3 double}    {8×3 double}    {8×3 double}    {5×3 double}

T2.T1

ans = 1×1 cell array
    {8×3 double}

For the purpose of power point slide, I guess the above suggested solution with evail is fine.

However, for other applications, please read this:

https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval