MATLAB Function Reference

sort - Sort array elements in ascending or descending order

Syntax

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

Description

B = sort(A) sorts the elements along different dimensions of an array, and arranges those elements in ascending order.

Integer, floating-point, logical, and character arrays are permitted. Floating-point arrays can be complex. For elements of A with identical values, the order of these elements is preserved in the sorted list. When A is complex, the elements are sorted by magnitude, i.e., abs(A), and where magnitudes are equal, further sorted by phase angle, i.e., angle(A), on the interval . If A includes any NaN elements, sort places these at the high end.

B = sort(A,dim) sorts the elements along the dimension of A specified by a scalar dim.

B = sort(...,mode) sorts the elements in the specified direction, depending on the value of mode.

[B,IX] = sort(A,...) also returns an array of indices IX, where size(IX) == size(A). If A is a vector, B = A(IX). If A is an m-by-n matrix, then each column of IX is a permutation vector of the corresponding column of A, such that

for j = 1:n
    B(:,j) = A(IX(:,j),j); 
end

If A has repeated elements of equal value, the returned indices preserve the original ordering.

Sorting Complex Entries

If A has complex entries r and s, sort orders them according to the following rule: r appears before s in sort(A) if either of the following hold:

• abs(r) < abs(s)

• abs(r) = abs(s) and angle(r)<angle(s)

  where

For example,

v = [1 -1 i -i];
angle(v)

ans =

         0    3.1416    1.5708   -1.5708
sort(v)

ans =

        0 - 1.0000i   1.0000
        0 + 1.0000i  -1.0000

Note   sort uses a different rule for ordering complex numbers than do max and min, or the relational operators < and >. See the Relational Operators reference page for more information.

Examples

Example 1

This example sorts a matrix A in each dimension, and then sorts it a third time, returning an array of indices for the sorted result.

A = [ 3 7 5
      0 4 2 ];

sort(A,1)

ans =
     0     4     2
     3     7     5

sort(A,2)

ans =
     3     5     7
     0     2     4

[B,IX] = sort(A,2)

B =
     3     5     7
     0     2     4

IX =
     1     3     2
     1     3     2

Example 2

This example sorts each column of a matrix in descending order.

A = [ 3  7  5
      6  8  3
      0  4  2 ];

sort(A,1,'descend')

ans =
     6   8   5
     3   7   3
     0   4   2

This is equivalent to

sort(A,'descend')

ans =
     6   8   5
     3   7   3
     0   4   2

See Also

issorted, max, mean, median, min, sortrows, unique

smooth3

sortrows