Logical comparison (>= to be specific) between each element (row) of a column vector, and all elements inside each row of a matrix having same number or rows, respectively

Question

Jonathan Morcos 2020-11-25

0
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https://ww2.mathworks.cn/matlabcentral/answers/662358-logical-comparison-to-be-specific-between-each-element-row-of-a-column-vector-and-all-elemen

评论： Jonathan Morcos 2020-11-25

I am wondering if there is a better/faster way to do this, perhaps without a for loop?

Say, I have a 30x50 matrix A, and a 30x1 column vector B. I want to procuce a 30x50 logical matrix C, where each element of C is 1 if the corresponding element of A is greater than or equal to the element of B located on the same row as that element.

For a small example:

>> A = [1 2 3 4 5 6; 7 8 9 10 11 12; 13 14 15 16 17 18];
B = [4 10 16]';
%numbers are in ascending order to simplify example
C = false(3,6);
c = 1;
for k = B'
   C(c,:) = (A(c,:) >= k);
   c = c + 1;
end

The output:

C
C =
  3×6 logical array
   0   0   0   1   1   1
   0   0   0   1   1   1
   0   0   0   1   1   1

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Answer 1

Stephen23 2020-11-25

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https://ww2.mathworks.cn/matlabcentral/answers/662358-logical-comparison-to-be-specific-between-each-element-row-of-a-column-vector-and-all-elemen#answer_556173

编辑：Stephen23 2020-11-25

在 MATLAB Online 中打开

A = [1,2,3,4,5,6;7,8,9,10,11,12;13,14,15,16,17,18]
A = 3×6
     1     2     3     4     5     6
     7     8     9    10    11    12
    13    14    15    16    17    18
B = [4;10;16]
B = 3×1
     4
    10
    16
C = A>=B % requires >=R2016b
C = 3x6 logical array
   0   0   0   1   1   1
   0   0   0   1   1   1
   0   0   0   1   1   1
C = bsxfun(@ge,A,B) % for earlier versions
C = 3x6 logical array
   0   0   0   1   1   1
   0   0   0   1   1   1
   0   0   0   1   1   1