Retrieving minimum values for parts of a matrix

Hi, I have a matrix containing different rows with values for several years. I need to retrieve the minimum value corresponding to each year. For example: A=[ 1958 2; 1958 3; 1959 4; 1959 5; 1959 6 ] The result matrix that I need would be: B=[ 1958 2; 1959 4 ]

Could you please help with this? Thanks

Answer 1

[Azzi Abdelmalek]

A=[ 1958 2; 1958 3; 1959 4; 1959 5; 1959 6 ] 
[ii,jj,kk]=unique(A(:,1))
out=[ii accumarray(kk,(1:numel(kk))',[],@(x) min(A(x,2)))]

Answer 2

[Matt J]

[i,~,s]=find( accumarray(A(:,1), A(:,2),[],@min )  );

B=[i,s]

[Matt J]

You can be a bit more memory-conservative by making modifications like this,

[i,j,s]=find( accumarray(A(:,1)-1949, A(:,2),[],@min )  ); 

B=[i+1949,s]