sort

Sorting numbers in an array

Usages

B = sort(A)

[B, I] = sort(A)

• It sorts elements of A in ascending order.
• If A is a vector, it sorts along the longer dimension.
• If A is a matrix or multi-dimensional array, it sorts along the first non-singleton dimension.
• If A is complex, it sorts by moduli, and then by the phase angles if two elements have the same moduli.
• If A is a character array, it sorts by the 16-bit scalar values.
• I contains indices of the sorted elements.

B = sort(A, k)

B = sort(A, direction)

B = sort(A, k, direction)

[B, I] = sort(A, k)

[B, I] = sort(A, direction)

[B, I] = sort(A, k, direction)

• A, B and I are as specified in the above usages.
• It sorts elements of A along the k-th dimension in the order specified by direction.
• k should be a real positive integer scalar.
• When k is not provided, it sorts along the first non-singleton dimension of A.
• direction should be either 'ascend' or 'descend'.
• When direction is not provided, it sorts in ascending order.

B = sort(A, name1, value1, ..., nameN, valueN)

B = sort(A, k, name1, value1, ..., nameN, valueN)

B = sort(A, direction, name1, value1, ..., nameN, valueN)

B = sort(A, k, direction, name1, value1, ..., nameN, valueN)

[B, I] = sort(A, name1, value1, ..., nameN, valueN)

[B, I] = sort(A, k, name1, value1, ..., nameN, valueN)

[B, I] = sort(A, direction, name1, value1, ..., nameN, valueN)

[B, I] = sort(A, k, direction, name1, value1, ..., nameN, valueN)

• The inputs A, k and direction, and outputs B and I are as specified in the above usages.

• The names should be either MissingPlacement or ComparisonMethod.

  • MissingPlacement should be either auto, first or last. See the table below for details.
  • ComparisonMethod should be either auto, real or abs. See the table below for details.

  Name	Value	Meaning
  MissingPlacement	auto	Default value. Missing elements come first when it sorts in the descending order. Missing elements come last when it sorts in the ascending order.
  -	first	Missing elements come first.
  -	last	Missing elements come last.
  ComparisonMethod	auto	Default value. Sort by real parts when A is real. Sort by moduli when A is complex.
  -	real	Sort by real parts for real and complex numbers. Sort by imaginary parts when two complex numbers have the same real parts.
  -	abs	Sort by absolute values for real numbers. Sort by moduli for complex numbers. If two complex numbers have equal moduli, it sorts by the phase angles.

Examples

• Sorting a character array consisting of captial letters.

Input

% Random ASCII values of captial letters
a = randi(26,1,20)+64;
% Convert to character array
c = char(a)
% Sorting
sort(c)

Output

c = 
BWIRYRNTDIPEDLJWPHPB

ans = 
BBDDEHIIJLNPPPRRTWWY

• Sorting a vector in ascending order along the longer dimension.

Input

A = rand(1,5)
[B,I] = sort(A)

Output

A = 1e-1 × 
 5.4456   1.3455   4.6364   2.0770   7.7713

B = 1e-1 × 
 1.3455   2.0770   4.6364   5.4456   7.7713

I = 
 2.0000   4.0000   3.0000   1.0000   5.0000

• Sorting a matrix in ascending order along the first nonsingleton dimension.

Input

A = rand(3,4)
[B,I] = sort(A)

Output

A = 1e-1 × 
 3.8998   3.8172   9.0582   3.1150
 9.2799   1.9726   9.3383   0.7341
 8.4704   0.5577   3.0939   5.0950

B = 1e-1 × 
 3.8998   0.5577   3.0939   0.7341
 8.4704   1.9726   9.0582   3.1150
 9.2799   3.8172   9.3383   5.0950

I = 
 1.0000   3.0000   3.0000   2.0000
 3.0000   2.0000   1.0000   1.0000
 2.0000   1.0000   2.0000   3.0000

• Sorting a matrix in descending order along the second nonsingleton dimension.

Input

A = rand(3,4)
[B,I] = sort(A,2,'descend')

Output

A = 1e-1 × 
 0.5282   0.1593   2.9196   5.8984
 4.7364   0.9964   0.1307   2.9491
 9.0733   8.7286   6.5544   9.4573

B = 1e-1 × 
 5.8984   2.9196   0.5282   0.1593
 4.7364   2.9491   0.9964   0.1307
 9.4573   9.0733   8.7286   6.5544

I = 
 4.0000   3.0000   1.0000   2.0000
 1.0000   4.0000   2.0000   3.0000
 4.0000   1.0000   2.0000   3.0000

• Sorting a character vector with the emoji character 😱. The scalar values of 😱 is [55357 56881]. The order of the scalar values remains unchanged when it is sorted in ascending order. Hence, it is encoded correctly in the sorted vector. Nevertheless, when it is sorted in descending order, it becomes [56881 55357]. Therefore, it cannot be encoded correctly (displaed as ��) in the sorted vector. ⚠️⚠️ As a rule of thumb, sorting an array with Unicode characters may give unexpected errors.

Input

sort('😱 oh my god!')
sort('😱 oh my god!','descend')

Output

ans = 
   !dghmooy😱

ans = 
��yoomhgd!