CODEWITHSUNDEEP
matlabmatrix
bzak
bzak

Reputation: 563

reducing matrices under certain conditions -Part 3-

M is a matrix composed of several submatrix Ai such that Ai(1:3,j) is the same vector for j = 1,...,size(Ai,2)

M = [1022  3001  4451 1022 1022  3001 3001 1022 4451 1022;
      112    45    10  112  112    45   45  112   10   11;
      500    11    55  500  500    11   11  500   55   88;
        2     6     6    5   71     2   71   88    2    2]



A1 = [1022 1022 1022 1022;
       112  112  112  112;
       500  500  500  500;
         2    5   71   88]

A2 = [3001 3001 3001;
        45   45   45;
        11   11   11;
         6    2   71]

A3 = [4451 4451;
        10   10;
        55   55;
         6    2]

A4 = [1022;
        11;
        88;
         2]

V = [2 71 6 9]

The only initial data for this problem are M and V.

my goal is to eliminate all sub-matrix Ai of M, if Ai(4,:) does not contains at least numel(V)-2 values of V.

for my example A1, A2 and A3 verify this condition. The expected output (order of columns is not important):

[1022 1022 1022 1022 3001 3001 3001 4451 4451 ;
  112  112  112  112   45   45   45   10   10;
  500  500  500  500   11   11   11   55   55;
    2    5   71   88    6    2   71    6    2]

how to change the following code to solve my problem:

[~,~,idx] = unique(M(1:3,:)','rows')  %//'
valid = ismember(M(4,:),V)
valid_idx = accumarray(idx(valid),M(4,valid).',[],@(x) ...
                                 numel(unique(x)))>=numel(V) %//'
out = M(:,ismember(idx,find(valid_idx)))

Upvotes: 1

Views: 52

Answers (1)

Divakar
Divakar

Reputation: 221624

See if this works for you -

%// ID columns of M based on the uniquenes of the first thre rows
[~,~,idx] = unique(M(1:3,:).','rows')  %//'

%// For each ID detect if it satisfies the ">= numel(V)-2" criteria 
matches = accumarray(idx(:),M(4,:)',[],@(x) sum(ismember(V,x))>=numel(V)-2 )

%// Use the valid ID's to select the valid unique groups for desired output
out = M(:,ismember(idx,find(matches)))

Upvotes: 1

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