How to delete multiple rows from a table using a for loop (with a condition)?

I would like to delete multiple rows form a table (imported from Excel).

I have "n" number of rows with 5 columns (Var1,..........,Var5). Now if in column 5 (Var5), there is value greater than 0, I want that row and the next three rows to be deleted.

Answer 1

[Jeremy Hughes]

I wouldn't use a for loop. MATLAB excells at array operations.

A = randn(12,5); % Make some data with positive and negative values
A(1:4:5) = -abs(A(1:4:5));
A(end-4:end) = -abs(A(end-4:end));

T = array2table(A)

T = 12×5 table
       A1           A2          A3          A4          A5   
    _________    ________    ________    ________    ________

     -0.18657     0.76498     0.23522    -0.86791     0.35787
      0.74813     0.73723    -0.13228     0.05872     -1.1772
       1.4034     -1.6129    -0.55285      2.2033     0.20268
      0.91163       0.915     -1.3487    -0.31358     0.16887
      -1.3759      1.4728     0.98564     -1.0473     0.34148
     -0.68973    -0.28485    -0.98694     0.29496      1.4129
       2.4566     -0.9063     -1.3356     -1.1073      2.1731
    -0.068694     -0.3263     0.90646    -0.19821     -1.1389
       1.1861      1.0306      3.1811     -2.0224    -0.60713
    -0.044051    -0.62426     0.72973    -0.58808    -0.66111
      0.46205     0.12273      1.0989    0.013466      -1.363
     -0.63828     0.81857    -0.54734     0.59388    -0.76208

rowIdx = find(T.A5 > 0);
rowIdx = rowIdx(:) + (0:3); % expands column + row
T(rowIdx,:) = [] % deletion

T = 2×5 table
       A1         A2          A3          A4          A5   
    ________    _______    ________    ________    ________

     0.46205    0.12273      1.0989    0.013466      -1.363
    -0.63828    0.81857    -0.54734     0.59388    -0.76208

You can also only check every fourth row, but there's some tricky math.

rowIdx = find(T.A5(1:4:end) > 0) % check every 4th entry will result  in the "block" index though
rowIdx = 4*(rowIdx-1)+1; % re-align to the right places in the original array
rowIdx = rowIdx(:) + (0:3); % expands column + row
T(rowIdx,:) = [] % deletion

T = 2×5 table
       A1         A2          A3          A4          A5   
    ________    _______    ________    ________    ________

     0.46205    0.12273      1.0989    0.013466      -1.363
    -0.63828    0.81857    -0.54734     0.59388    -0.76208

[Hasnain Raja Muhammad]

Thanks, it works perfectly fine!