根据第二个矩阵(MATLAB)中给出的顺序对矩阵进行排序

Question

我有一个排序的bigmatrix.但是,我需要按照另一个矩阵(col. 1 here for both matrices)中ID的顺序重新排序.我怎么能用矢量化呢？例如:

bigmat = [ ...
            1 10 ; 
            1 30 ; 
            1 40 ; 
            2 1  ; 
            2 11 ; 
            3 58 ; 
            4 2  ;
            4 5 ] ;

ordermat = [ 2 ; 1 ; 4 ; 3 ; 6] ;       % Integer IDs

finalans = [ ...
            2 1  ; 
            2 11 ; 
            1 10 ; 
            1 30 ; 
            1 40 ;
            4 2  ;
            4 5  ;
            3 58 ; ] ;

ordermat在bigmat 中可能不存在所有一些ID(此处为整数).它们可以被忽略,如上所示id = 6.谢谢!

Answer 1

%# Input values:
bigmat = [1 10; 1 30; 1 40; 2 1; 2 11; 3 58;  4 2; 4 5];
ordermat = [ 2 ; 1 ; 4 ; 3 ; 6] ;   

%# Make a look-up table that tells us the relative order for each order id
sortmat(ordermat) = 1:length(ordermat);

%# Extract the order ID's from the big matrix
keys = bigmat(:,1);

%# Get the new ordering
new_key = sortmat(keys);

%# Sort the new ordering, remembering the permutation necessary
[~, permutation] = sort(new_key);

%# Apply the permutation to the big matrix
finalans = bigmat(permutation, :);