Compare each row of array, then return the number of rows that are equal

Question

monkey_matlab 2016-11-20

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https://ww2.mathworks.cn/matlabcentral/answers/313164-compare-each-row-of-array-then-return-the-number-of-rows-that-are-equal

回答： Star Strider 2016-11-20

采纳的回答： Star Strider

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Hello, I was trying to compare each row, one by one, and then return the number of rows that are equal.

For example, for the arrays A and B:

A = [1;1;2;3];
B = [2;1;1;3];

The rows that are equal to each other = 2...that is, rows 2 and 4 are equal. I tried the command:

all(A()==B())

but got the ans = 0.

Any help is appreciated.

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Answer 1

Star Strider 2016-11-20

1
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/313164-compare-each-row-of-array-then-return-the-number-of-rows-that-are-equal#answer_244030

在 MATLAB Online 中打开

Try this:

A = [1;1;2;3];
B = [2;1;1;3];
C = [A, B];
Equal_Rows = find(diff(C,[],2) == 0)
Equal_Rows =
     2
     4

NOTE — This only reliably works with integers. For floating point numbers, especially those that are the result of calculations, you would need to incorporate a tolerance, probably involving a ‘greater-than-or-equal to’ and a ‘less-than-or-equal-to’ condition. See Why is 0.3 - 0.2 - 0.1 (or similar) not equal to zero? for an explanation.