![A := matrix([[a, 12, 34], [b, 32, 54], [c, 24, 45], [d, 33, 42], [e, 21, 60]])](images/sort1.gif)
Creating a Sorting Procedure
The commands and program below allow the easy sorting and analysis of a set of data.
| > | with(linalg): |
Warning, the protected names norm and trace have been redefined and unprotected
Create a data matrix.
| > | A:=matrix(5,3,[a,12,34,b,32,54,c,24,45,d,33,42,e,21,60]); |
Below we create a program for sorting the data based on a particular column in ascending order.
| > |
sortcol := proc(A,N) |
| > | local i,j,n; |
| > | n := rowdim(A); |
| > | for j from 1 to n-2 do |
| > | for i from 1 to n-1 do |
| > | if A[i,N] > A[i+1,N] then |
| > | A := swaprow(A,i,i+1); |
| > | fi: |
| > | od: od: |
| > | evalm(A); |
| > | end: |
Use the routine for sorting columns 2 and 3.
| > | sortcol(A,2); |
![matrix([[a, 12, 34], [e, 21, 60], [c, 24, 45], [b, 32, 54], [d, 33, 42]])](images/sort2.gif)
| > | sortcol(A,3); |
![matrix([[a, 12, 34], [d, 33, 42], [c, 24, 45], [b, 32, 54], [e, 21, 60]])](images/sort3.gif)
Compute the average of the second column.
| > | with(stats): |
| > | A2 := col(A,2); |
![A2 := vector([12, 33, 24, 32, 21])](images/sort4.gif){kind=small}
| > | A2 := convert(A2,list); |
![A2 := [12, 33, 24, 32, 21]](images/sort5.gif){kind=small}
| > | describe[mean](A2); evalf(%); |
| > |