Matlab - Return only the rows of a matrix 'A' that not contain some values of matrix 'B'

Question

How do I return only the rows of a matrix 'A' that not contain some values (These values are an array 'B')?

  A = {'A1',  5  'P01,P02,P03,P04,P07'; 
        'A2'  7,  'P07,P10';
        'A3'  8,  'P07,P09';
        'A4'  8,  'P10,P11'};

    B = { 'P07'; 'P10'; 'P11'};

I need to return only:

'A1'  ( P01,P02,P03,P04 not exist in B)
'A3'  (P09 not exist in B)

Thanks in advance for your help

Straightforward with a `for loop` going through the rows of cell array A, then checking the third element with `strcmp` for containment of any values of B; if not so returning the first element of each of these rows... — NoDataDumpNoContribution, Jan 09 '14 at 15:29
@Mad Physiscist. You're right. strfind and a second loop over B with early breakout would do the trick — NoDataDumpNoContribution, Jan 09 '14 at 15:46
@TimmelsNear. Are you sure you need better performance here? For better performance I would replace the PXX literals first with some numbers like powers of 2 and then doing bit arithmetic. — NoDataDumpNoContribution, Jan 09 '14 at 15:49

Mad Physicist · Accepted Answer · 2014-01-09T16:19:07.453

3

Since you are dealing with weirdly shaped cell arrays and some strange string operations, I do not know how to solve this cleanly with one statement. You can try the following loop:

R = {};
for i = 1 : size(A, 1)
    test = strsplit(A{i, 3}, ',');
    for j = 1 : length(test)
        if nnz(strcmp(B, test{j})) == 0
            R = [R; A(i, 1)];
            break;
        end
    end
end

The result is:

R = 

    'A1'
    'A3'

Of course these calculations could be made much faster if it was possible to work with just the numerical components of each search string in an actual matrix rather than cell arrays of strings.

edited Jan 09 '14 at 16:19

answered Jan 09 '14 at 15:32

Mad Physicist

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@TimeIsNear. Fixed. I misunderstood your condition – Mad Physicist Jan 09 '14 at 16:19
Thanks for your help. Little question why using "nnz"? – TimeIsNear Jan 09 '14 at 23:19
1

@TimeIsNear `nnz` computes the Number of Non-Zero elements in an array. It is equivalent to using `sum` on a `logical`. In this case, I use it to check that `strcmp` did not find a match in any of the cells of `B`. – Mad Physicist Jan 10 '14 at 04:47

Matlab - Return only the rows of a matrix 'A' that not contain some values of matrix 'B'

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