Referencing specific dimensions of an array

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alexander 2014-12-30

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https://ww2.mathworks.cn/matlabcentral/answers/168549-referencing-specific-dimensions-of-an-array

评论： alexander 2014-12-30

Hello,

I have a rectangular matrix and I am trying to determine if values in each row are equal. I built a function that will check an array to see if all numbers are equal. I want to avoid using a for loop.

I tried to add a fourth column to an existing matrix with the result of the function.

I tried;

x(:,4)=three(x(:,:))

as well as several other variations. how can I imply to evaluate only each row?

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Answer 1

Sean de Wolski 2014-12-30

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x(:,4) = all(bsxfun(@eq,x(:,1),x(:,2:3)),2)

The fourth column will not be true where the first three columns are equal.

I believe this is what you want. If it's not, exactly what do you want? A small example with inputs->operation->expected output would be ideal

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alexander 2014-12-30

thanks fo rthe answer

it took me a little while to see what you did there but I think I understand. I am not just looking for equality though. I am checking if they are all the same value. Below is my funtion

function [ c ] = three( x )
s=find(x==6);
if length(s)==3
    c=true;else c=false;
end
end

alexander 2014-12-30

So my way works but you's is better. I used

x(:,4) = all(bsxfun(@eq,[6],x(:,1:3)),2)

Where I can replace the 6 with whatever number I require. I still wonder though from the original question. is their some syntax that would allow what I attempted?

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