Set conditions between two matrices
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First question :* I have two matrices (360x1) and I want to set conditions to generate a third matrix (360x1). I want to compare the first row of the first matrice [A] to the first row of the second matrice [B], up until the 360th row of the first matrix to the 360th rows of the second matrix.
This is what I tried to write:
E = ones(360,1);
for r=1:360
for c=1:1
for k=1:360
if A(k,1) == B(k,1)
E(r,c)= 2;
elseif A(k,1) > B(k,1)
E(r,c)= -1;
else A(k,1) < B(k,1)
E(r,c)= 0;
end
end
end
...and it doesn't work.
Second question : I would like to display a different text instead of the value '2', '-1' and '0'.
Thank you in advance !
1 个评论
Jan
2018-1-5
"It doesn't work" is too lean to describe the problem you have. Do you get an error message or does the result differ from your expectations? Currently the comparison does not depend on r.
采纳的回答
Guillaume
2018-1-5
If you're happy with having 1 when A(k)>B(k), 0 when A(k)==B(k) and -1 when A(k)<B(k), then the answer is simply:
E = sign(A-B)
No loop needed. If you do want -1, 2, 0 in the above case, respectively, then:
vals = [0 2 -1];
E = vals(sign(A-B) + 2)
"I would like to display a different text instead of the value '2', '-1' and '0'"
First, you're mixing up text and numeric. Your code, and the answers above, generate numerical arrays. There is no text. You could have text instead, e.g.:
vals = {'smaller', 'equal', 'greater'}; %for text, has to be a cell array
E = vals(sign(A-B) + 2)
but be aware that working with text is a bit harder than working with numerical matrices.
Finally, if you're working with vectors use linear indexing (i.e. A(k)) rather than subscript indexing (i.e A(k, 1)). The former will work regardless of the direction of the vector, the latter will not.
更多回答（1 个）
Pawel Jastrzebski
2018-1-5
编辑：Pawel Jastrzebski
2018-1-5
clear all;
clc;
% DATA
A = randi(50,1,360,'int16');
B = randi(50,1,360,'int16');
% LOGICAL VECTORS
AB_Equal = A == B
A_Greater = A > B
B_Greater = ~(AB_Equal | A_Greater)
% NEW MATRIX
C = zeros(1,length(A));
C(A == B) = 2;
C(A > B) = -1;
% IF you want to swap the -1,0,2 for text classification, i.e.:
% -1 = 'a'
% 0 = 'b'
% 2 = 'c'
cVal = '0';
cTxt = repmat(cVal,1,length(A));
cTxt(AB_Equal) = 'c';
cTxt(A_Greater) = 'a';
cTxt(B_Greater) = 'b';
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