FreeMat
SORT Sort

Section: Array Generation and Manipulations

Usage

Sorts an n-dimensional array along the specified dimensional. The first form sorts the array along the first non-singular dimension.

  B = sort(A)

Alternately, the dimension along which to sort can be explicitly specified

  B = sort(A,dim)

FreeMat does not support vector arguments for dim - if you need A to be sorted along multiple dimensions (i.e., row first, then columns), make multiple calls to sort. Also, the direction of the sort can be specified using the mode argument

  B = sort(A,dim,mode)

where mode = 'ascend' means to sort the data in ascending order (the default), and mode = 'descend' means to sort the data into descending order.

When two outputs are requested from sort, the indexes are also returned. Thus, for

  [B,IX] = sort(A)
  [B,IX] = sort(A,dim)
  [B,IX] = sort(A,dim,mode)

an array IX of the same size as A, where IX records the indices of A (along the sorting dimension) corresponding to the output array B.

Two additional issues worth noting. First, a cell array can be sorted if each cell contains a string, in which case the strings are sorted by lexical order. The second issue is that FreeMat uses the same method as MATLAB to sort complex numbers. In particular, a complex number a is less than another complex number b if abs(a) < abs(b). If the magnitudes are the same then we test the angle of a, i.e. angle(a) < angle(b), where angle(a) is the phase of a between -pi,pi.

Example

Here are some examples of sorting on numerical arrays.

--> A = int32(10*rand(4,3))

A = 
 8 2 8 
 0 5 5 
 2 5 7 
 3 7 1 

--> [B,IX] = sort(A)
B = 
 0 2 1 
 2 5 5 
 3 5 7 
 8 7 8 

IX = 
 2 1 4 
 3 2 2 
 4 3 3 
 1 4 1 

--> [B,IX] = sort(A,2)
B = 
 2 8 8 
 0 5 5 
 2 5 7 
 1 3 7 

IX = 
 2 1 3 
 1 2 3 
 1 2 3 
 3 1 2 

--> [B,IX] = sort(A,1,'descend')
B = 
 8 7 8 
 3 5 7 
 2 5 5 
 0 2 1 

IX = 
 1 4 1 
 4 2 3 
 3 3 2 
 2 1 4 

Here we sort a cell array of strings.

--> a = {'hello','abba','goodbye','jockey','cake'}

a = 
 [hello] [abba] [goodbye] [jockey] [cake] 

--> b = sort(a)

b = 
 [abba] [cake] [goodbye] [hello] [jockey]