selecting rows from C with associated values in D, while using A and B values as references to produce E and F matrices

Asked by JL on 14 Sep 2019

Latest activity Edited by per isakson on 15 Sep 2019

1 view (last 30 days)

Hi everyone, I have 2 matrices, A and B, that I want to use as reference to draw out certain rows in C and attached associated values from D.

A = [1 2];
B = [1 3];
C = [  1	19	18	4	3	0	0	0	0	0	0  
       1	19	2	17	6	7	5	4	3	2	0
       1	16	15	17	6	7	5	4	3	2	0
       1	19	2	3	0	0	0	0	0	0	0
       1	16	15	14	9	8	7	5	4	3	2
       1	16	15	14	9	6	5	4	3	2	0
       1	2	3	0	0	0	0	0	0	0	0
];
D = [0.1
     0.3
     0.4
     0.8
     0.9
     0.11
     0.2
     ];

my end results for E and F should be:

E = [0.1     1	19	18	4	3	0	0	0	0	0	0
     0.8     1	19	2	3	0	0	0	0	0	0	0
     0.2     1	2	3	0	0	0	0	0	0	0	0    
    ];
F = [0.3     1	19	2	17	6	7	5	4	3	2	0
     0.4     1	16	15	17	6	7	5	4	3	2	0
     0.9     1	16	15	14	9	8	7	5	4	3	2
     0.11    1	16	15	14	9	6	5	4	3	2	0
    ];

2 Comments

madhan ravi on 14 Sep 2019

Difficult to understand , illustrate with a short example.

JL on 14 Sep 2019

Hi Madhan, so basically, put them on E and F based on their first and last number (ignore zero in each rows). For examples, for [1 3], I select the rows in C to put in E with a row starting with 1 and ending with 3 (like I said, ignore zeros)

2 Answers

Link

Answer by Bruno Luong on 14 Sep 2019

Edited by Bruno Luong on 14 Sep 2019

Accepted Answer

A = [1 2];
B = [1 3];
C = [  1	19	18	4	3	0	0	0	0	0	0;
       1	19	2	17	6	7	5	4	3	2	0;
       1	16	15	17	6	7	5	4	3	2	0;
       1	19	2	3	0	0	0	0	0	0	0;
       1	16	15	14	9	8	7	5	4	3	2;
       1	16	15	14	9	6	5	4	3	2	0;
       1	2	3	0	0	0	0	0	0	0	0
    ];
D = [0.1;
    0.3;
    0.4;
    0.8;
    0.9;
    0.11;
    0.2
    ];
[i,j] = find(C);
getC = @(pickfun) C(sub2ind(size(C),(1:size(C,1))',accumarray(i(:),j(:),[],pickfun)));
filtFun = @(x) ismember([getC(@min),getC(@max)],x,'rows');
b = filtFun(B);
E = [D(b,:),C(b,:)]
b = filtFun(A);
F = [D(b,:),C(b,:)]

1 Comment

JL on 14 Sep 2019

Thanks Bruno! That was really helpful :)

Link

Answer by per isakson on 14 Sep 2019

Edited by per isakson on 15 Sep 2019

The script

%%
ixe = [1,4,7];
E = cat( 2, D(ixe), C(ixe,:) );
ixf = setdiff( [1:7], ixe );
F = cat( 2, D(ixf), C(ixf,:) );

calculates E and F that agrees with your sample.

However, I cannot see how the rows 1, 4 and 7, honors the rules you provide in your comment.

In response to comment

ixe = find_rows( C, B ); 
E = cat( 2, D(ixe), C(ixe,:) );
ixf = find_rows( C, A ); 
F = cat( 2, D(ixf), C(ixf,:) );
%
function    ix_rows = find_rows( C, FL );
    ix_rows = nan( 1, size(C,1) );
    for jj = 1 : size( C, 1 )
        row = C(jj,:);
        row(row==0) = [];
        if row(1)==FL(1) && row(end)==FL(2)
            ix_rows(jj) = jj;
        end
    end
   ix_rows( isnan( ix_rows ) ) = [];
end

1 Comment

JL on 14 Sep 2019

Hi isakson, can it select automatically rather than selecting 1 4 7 to put to E then putting the rest in F? The reason being, I have 3000 over rows and they are not just for E and F.

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