How to create a matrix with the data of a comparison, upper triangular the percentage of similarity and lower triangular the times that were compared?

Question

German Preciat Gonzalez 2016-6-29

0
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https://ww2.mathworks.cn/matlabcentral/answers/292991-how-to-create-a-matrix-with-the-data-of-a-comparison-upper-triangular-the-percentage-of-similarity

评论： German Preciat Gonzalez 2016-6-29

I have a matrix with N rows and 4 columns. Each row represent a comparison of a file between different sources, columns represent the sources, each of the elements of the matrix can take values form 1-4 or NaN.

Column 1 have values of 1 or NaN

Column 2 have values of 1,2 or NaN

Column 3 have values of 1,2,3 or NaN

Column 4 have values of 1,2,3,4 or NaN

An example is:

M  =  [1    NaN  3    3;
       1    2    NaN  2;
       NaN  2    2    4;
       1    2    1    1;
       1    1    3    1;
       1    1    3    4]

For example in row 1

[1 NaN 3 3]

sources 3 and 4 are similar, in source 2 there is not data, and source 1 is no similar to any other.

If I compare of M, source 1 with source 2 it was compared 4 times (because of NaN in M(1,2) and M(3,1)) and the similarity is 50% (2/4)

I would like to have a square matrix (4x4) with this data where the upper triangular matrix is the percentage of similarity and the lower triangular matrix the times that were compared, like this:

  50*   25    40
     4*    0    25    40
   4     0    40
   5     5     0

The stars are for the example when I compared source 1 with source 2 (indexes (1,2) and (2,1)).

I did that using a lot of IF and the script looks so ugly haha, "If" you can recomend me something I would really appreciate it

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Answer 1

Andrei Bobrov 2016-6-29

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/292991-how-to-create-a-matrix-with-the-data-of-a-comparison-upper-triangular-the-percentage-of-similarity#answer_227155

在 MATLAB Online 中打开

a = permute(M,[3,2,1]);
b = permute(M,[2,3,1]);
x = sum(bsxfun(@eq,a,b),3);
y = sum(~isnan(bsxfun(@plus,a,b)),3);
out = tril(y,-1) + triu(x./y'*100,1);