Matlab:如何在矩阵A上进行此转换? [英] Matlab: How I can make this transformation on the matrix A?

问题描述

我有一个矩阵A 4x10000，我想用它找到另一个矩阵C.

I have a matrix A 4x10000, I want to use it to find another matrix C.

我将通过一个简单的例子来简化我的问题:

I'll simplify my problem with a simple example:

来自矩阵A

20     4     4    74    20    20     
36     1     1    11    36    36     
77     1     1    15    77    77     
 3     4     2     6     7     8  

首先，我想找到一个中间实体B:

I want, first, to find an intermediate entity B:

             2     3     4     6     7    8     

[20 36 77]   0     1     0     0     1    1     3

[4   1  1]   1     0     1     0     0    0     2

[74 11 15]   0     0     0     1     0    0     1

如果第一行和向量的对应值在左侧，则将1设为矩阵A的一列.

we put 1 if the corresponding value of the first line and the vector on the left, made ​​a column in the matrix A.

实体B的最后一列是每行1的总和.

the last column of the entity B is the sum of 1 of each line.

最后，我想要一个矩阵C，该矩阵C由留在实体B中的矢量组成，但前提是1的总和大于或等于2.

at the end I want a matrix C, consisting of vectors which are left in the entity B, but only if the sum of 1 is greater than or equal to 2.

以我的示例为例:

     20  4
C =  36  1
     77  1

N.B:对于我的问题，我使用矩阵A 4x10000

N.B: for my problem, I use a matrix A 4x10000

推荐答案

查看它是否对您有用-

%// We need to replace this as its not available in your old version of MATLAB:
%// [unqcols,~,col_match] = unique(A(1:end-1,:).','rows','stable') %//'

A1 = A(1:end-1,:).'; %//'
[unqmat_notinorder,row_ind,labels] = unique(A1,'rows');
[tmp_sortedval,ordered_ind] = sort(row_ind);

unqcols = unqmat_notinorder(ordered_ind,:);

[tmp_matches,col_match] = ismember(labels,ordered_ind);
%// OR use - "[tmp2,col_match] = ismember(A1,out,'rows');"

C = unqcols(sum(bsxfun(@eq,col_match,1:max(col_match)),1)>=2,:).'; %//'
%// OR use - "C = out(accumarray(col_match,ones(1,numel(col_match)))>=2,:).'"

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