MATLAB: Finding maximum value between specific columns for each row

max column

Hi, May I ask about Finding maximum value between specific columns for each row?

Let's say I have A = [1 2 3 4 5; 6 7 8 9 10; 11 12 13 14 15; 16 17 18 19 20]. I would like to find maximum value for 2nd and 3rd colum for each row.

I should get B = [3; 8; 13; 18]. Could anyone please help me with that?

Thanks a lot in advance!

Best Answer

iwant = max(A(:,[2 3]),[],2)

Related Solutions

MATLAB: Find indices of a value in a particular row or column in relation to the full matrix

Why use find() when min() and max() are more directly suited for finding the min and max values and indexes:

A=[1,2,3,4,5;,6,7,8,9,10;11,12,13,14,15;16,17,18,19,20;21,22,23,24,25]
[firstRowMaxValue, firstRowMaxIndex] = max(A(1, :))
[firstRowMinValue, firstRowMinIndex] = min(A(1, :))
[lastColMaxValue, lastColMaxIndex] = max(A(:, end))
[lastColMinValue, lastColMinIndex] = min(A(:, end))

MATLAB: Extract data from each row in a matrix if all columns in that row above a threshold

Here is an example:

 >> A = randi( 20, 10, 5 )   % Dummy example.
 A =
    17     4    14    15     9
    19    20     1     1     8
     3    20    17     6    16
    19    10    19     1    16
    13    17    14     2     4
     2     3    16    17    10
     6     9    15    14     9
    11    19     8     7    13
    20    16    14    20    15
    20    20     4     1    16
 >> threshold = 4 ;
 >> B = A(all( A > threshold, 2 ),:)
 B =
     6     9    15    14     9
    11    19     8     7    13
    20    16    14    20    15

PS: if you need to remove these rows, you can do it as follows:

 >> isAllAbove = all( A > threshold, 2 ) ;
 >> B = A(isAllAbove,:)
 B =
     6     9    15    14     9
    11    19     8     7    13
    20    16    14    20    15
 >> A(isAllAbove,:) = []     % or  A = A(~isAllAbove,:)
 A =
    17     4    14    15     9
    19    20     1     1     8
     3    20    17     6    16
    19    10    19     1    16
    13    17    14     2     4
     2     3    16    17    10
    20    20     4     1    16

Best Answer

Related Solutions

MATLAB: Find indices of a value in a particular row or column in relation to the full matrix

MATLAB: Extract data from each row in a matrix if all columns in that row above a threshold

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