lex_sort - lexicographic matrix rows sorting

Calling Sequence

[N, [k]]=lex_sort(M [,sel] [,'unique'])

Parameters

• M : real matrix
• N : real matrix
• k : column vector of integers

Description

N=lex_sort(M) sorts the rows (as a group) of the matrix M in ascending order. If required the output argument k contains the ordering: [N,k]=lex_sort(M) returns k such as N is uequal to M(k,:) .

N=lex_sort(M,sel [,'unique']) produces the same result as the following sequence of instructions:

[N,k]=lex_sort(M(:,sel) [,'unique']);
N=M(k,:)
   

The 'unique' flag has to be given if one wants to retain only unique rows in the result. Note that lex_sort(M,sel,'unique') retains only rows such that M(:,sel) are unique.

Examples

M=round(2*rand(20,3));

lex_sort(M)
lex_sort(M,'unique')
[N,k]=lex_sort(M,[1 3],'unique')

 

See Also

sort