Sorting a mixed text-numeric matrix (cell array) by one of its (numeric) columns

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z8080 2019-5-1

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评论： dpb 2019-5-1

I have an Excel spreadsheet whose rows I'd like to randomly shuffle and further use in Matlab. To that end, I'm reading the XLS into a cell array, generating random numbers into a column, then sorting by that column. This is proving to be problematic though, because of conflicting variable types. The code I used is:

    [num, txt, M] = xlsread(fileName);
    for row=2:row_N % generate random numbers in the D column
    	M(row,4) = num2cell(rand);
    end
    M = sortrows(M,4);

This leads to my matrix looking like this:

Because the D column contains numbers while there's text in the other columns, the sorting cannot be done (it says "Cell elements must be character arrays.").

I tried various conversions between numeric and cell variables, and also tried using 'readtable' instead of 'xlsread' - but there is always a problem, such that I cannot get this conflict solved.

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Answer 1

dpb 2019-5-1

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https://ww2.mathworks.cn/matlabcentral/answers/459592-sorting-a-mixed-text-numeric-matrix-cell-array-by-one-of-its-numeric-columns#answer_373118

在 MATLAB Online 中打开

    t=readtable(fileName,'readvariablenames',1);
    t.sort=rand(height(t),1);
    [~,ix]=sort(t.sort);
    t=t(ix,:);

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z8080 2019-5-1

I'd have thought 1 would work as well, but I got an error which went away when I replaced with true.. no matter, the solution proposed is very good, thanks again

dpb 2019-5-1

Ah!

Did you use 1 or '1' ? It's a numeric one, not character (altho T==>~0 so should still be ok altho I can see a test for other than logical or numeric)

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