Search parallel rows of a structures for common items in matlab

Question

I\'ve stored (row,col,val) information of

 key1:         (1,1) (1,2) (1,3) (4,2) (3,4)  
 attribute1:    2      3    4      2     5  

as follo

Answer 1

first use sort to achieve row-col order insensitivity, next use unique to handle row-col duplicates within each structure, and finally use ismember (with 'rows') to find common keys between the structures. note that I added an inner duplication to each structure to show the second stage effect:

% struct1
row1 = [1  1  1  2  4  3];
col1 = [1  2  3  1  2  4];
att1 = [2  3  4  6  2  5];
% struct2
row2 = [2  2  1  3  3];
col2 = [1  2  3  1  4];
att2 = [1  0  1  1  5];
% sort in 2nd dimension to get row-column indexes insensitive for order
idx1 = sort([row1(:) col1(:)],2);
idx2 = sort([row2(:) col2(:)],2);
% search for duplicates inside each struct
[idx1,~,bins1] = unique(idx1,'rows','stable');
att1 = accumarray(bins1,att1);
[idx2,~,bins2] = unique(idx2,'rows','stable');
att2 = accumarray(bins2,att2);
% search common entries
common1 = ismember(idx1,idx2,'rows');
row = idx1(common1,1);
col = idx1(common1,2);
common2 = ismember(idx2,[row col],'rows');
% add common values
att = att1(common1) + att2(common2);
Result.row = row';
Result.col = col';
Result.attribute = att';
disp(Result)

and you get:

Result = 
          row: [1 1 3]
          col: [2 3 4]
    attribute: [10 6 10]