Error in close calculation and plotting

Hey,

I have been using this code and it has worked really well in the past. It is giving me an error now. I'm attaching the file, pasting the code and the linked error. It would be great to have some help!

% detrended correlated Rs>0.7
[UClass,~,idx] = unique(detrend_correl_07_slope_1.id,'stable');
XYc = accumarray(idx, (1:numel(idx)).', [], @(x){detrend_correl_07_slope_1(x,:)})
XYc{3}
for k = 1:numel(XYc)
    B(:,k) = [XYc{k}{:,3} ones(size(XYc{k}{:,3}))] \ XYc{k}{:,4};
    detrend_correl_07_slope_1(k) = B(1,k);
end
slope_ln_data_11
slope_ln_data_11 =  slope_ln_data_11'
figure
tiledlayout(numel(XYc),1)
for k = 1:numel(XYc)
    nexttile
    plot(XYc{k}{:,3}, XYc{k}{:,4}, 'p')
    hold on
    L = [XYc{k}{:,3} ones(size(XYc{k}{:,3}))] * B(:,k);
    plot(XYc{k}{:,3}, L, '-r')
    hold off
    grid
    axis('padded')
    title("Slope = "+slope_ln_data_11(k))
end

It's throwing up the following error for this line of code

detrend_correl_07_slope_1(k) = B(1,k);

Error using () (line 115)

Subscripting into a table using one subscript (as in t(i)) is not supported. Specify a row

subscript and a variable subscript, as in t(rows,vars). To select variables, use t(:,i) or for

one variable t.(i). To select rows, use t(i,:).

Answer 1

[dpb]

That code could never have worked as is if detrend_correl_07_slope_1 was a table. You used the .id variable dot referencing earlier in the call to unique, you need the same here...the dot has somehow gotten lost. Use

detrend_correl_07_slope_1.(k) = B(1,k);

to reference each column k in turn.

[Nikita]

Thanks so much! This has been really helpful.

Answer 2

[Umar]

Hi @Nikita,I've identified the issue with your code. The error occurs because detrend_correl_07_slope_1 is a table, not a regular array. MATLAB tables cannot be indexed with single subscripts like detrend_correl_07_slope_1(k). They require two subscripts for rows and columns, or dot notation to access variables.

The problematic line is:

detrend_correl_07_slope_1(k) = B(1,k);

This worked previously because your data was likely imported as a numeric array rather than a table. Something has changed in how the data is being loaded or the MATLAB version you're using.

Here's the fix. Replace that line with this approach:

slope_ln_data_11 = zeros(numel(XYc), 1);
for k = 1:numel(XYc)
    B(:,k) = [XYc{k}{:,3} ones(size(XYc{k}{:,3}))] \ XYc{k}{:,4};
    slope_ln_data_11(k) = B(1,k);
end

Then if you need to add these slopes back to your table later, you can use:

detrend_correl_07_slope_1.slope = slope_ln_data_11';

This keeps your slope calculations in a regular numeric array where single-index subscripting works perfectly. The rest of your code should run without any changes.

According to the MathWorks documentation, tables require explicit row and column specification. You can access table data using table(rows, vars) syntax, curly braces table{rows, vars} to extract the underlying array, or dot notation table.VariableName for specific columns.

Let me know if you run into any other issues with this fix.

[Nikita]

Thanks so much! This has been really helpful.