MaplePrimes - answers and comments on Question, Sort Matrix elements in ascending or descending order

sort columns

Joe Riel — Thu, 13 Dec 2012 08:45:10 Z

To sort the columns, without creating a permutation Matrix, you could do

(m,n) := upperbound(M):
for j to n do
    M[..,j] := sort(M[..,j]);
end do:

Here's another approach for generating permutation lists/vectors.

matix Sort with permutation vector of the corresponding column

herclau — Fri, 14 Dec 2012 01:31:35 Z

Thanks to @Alec Mihailovs , in his reply from Forum, 2005
Sorting with Indices

How to implement this idea for a matrix or universalize to: List, Array, Vector, Matrix

My proposal for a matrix, I hope you guide me for improvement

# proc (M::Matrix)
local m, n, i, MI, MV, TT;
m, n := upperbound(M);
MI := Matrix(m, n);
MV := Matrix(m, n);
for i to n do
TT := ListTools:-Transpose(sort(ListTools:-Enumerate(convert(M[() .. (), i], list)), (a, b) -> a[2] <= b[2]));
MI[() .. (), i] := <(TT[1]>;
MV[() .. (), i] := <TT[2]>;
end do;
return MI, MV
end proc;

Gracias

List, ??, Vector, Matrix

herclau — Fri, 14 Dec 2012 20:52:01 Z

M := Matrix(6, 3, [2, 3, 3, 5, 7, 8, 12, 5, 9, -3, 4.1, 7, 7, 7, -3, 9, 3, 8]);M;

(1)

(2)

from Matlab
[b,n]=sort(A)

b =

-3.0000 3.0000 -3.0000

2.0000 3.0000 3.0000

5.0000 4.1000 7.0000

7.0000 5.0000 8.0000

9.0000 7.0000 8.0000

12.0000 7.0000 9.0000

n =

4 1 5

1 6 1

2 4 4

5 3 2

6 2 6
3 5 3

mSort := proc (mM::{Matrix, Vector, list})
local m, n, i, M, MI, MV, TT;
M := `if`(type(mM, Matrix), mM, convert(mM, Matrix));
m, n := upperbound(M);
MI := Matrix(m, n);
MV := Matrix(m, n);
for i to n do
TT := ListTools:-Transpose(sort(ListTools:-Enumerate(convert(M[() .. (), i], list)),(a, b) -> a[2] MI[() .. (), i] := ;
MV[() .. (), i] := ;
end do;
return MV, MI;
end proc:

M; mSort(M);

(3)

Ds := Matrix(4, 4, [-434.8482330, 0, 0, 0, 0, 336.3639763, 0, 0, 0, 0, 4.310248244, 0, 0, 0, 0, 94.17400829]);

(4)

mSort(LinearAlgebra[Diagonal](Ds));

(5)

mSort();

(6)

Download SortMatrix1.mw