MATLAB: Match vector with first column of matrix

matchingmatrixmatrix arraymatrix manipulation

I have a matrix 'Mat' and a vector 'v', I want to match the vector 'v' with the first row of 'Mat' such that I get an output 'res'. I tried using the ismember function and a code mentioned below
Mat=[1 356
 4 457
 7 91
 6 431
9 33
10 322  ]
v =[NaN 1 7 NaN 1  9 6 NaN 6 6]   
res= [NaN NaN
    1 356
    7 91
    NaN NaN
    1 356
    9 33
    6 431
    NaN NaN
    6 431
    6 431]
%%%%%%code I tried but did not work, it does not give numbers for repetative occurences of elemet in vector B
idx=setdiff(v,Mat(:,1)).';
ans=zeros(numel(idx),1);
idx=[idx' ans];
res=sortrows([Mat;idx]);

Best Answer

Simpler with just one ismember call and some basic indexing:
>> [idx,idy] = ismember(v(:),Mat(:,1));
>> res = [v(:),v(:)];
>> res(idx,2) = Mat(idy(idx),2)
res =
   NaN   NaN
     1   356
     7    91
   NaN   NaN
     1   356
     9    33
     6   431
   NaN   NaN
     6   431
     6   431
Related Question