What is sorting in MATLAB?

Sorting

Sorting is a concept in which elements are rearranged logically into a pattern where numbers either go from smaller to larger, or from larger to smaller numbers.

Sorting in MATLAB

There are many algorithms we can use for sorting, but in MATLAB, we can sort an array or matrix of numbers in MATLAB using the built-in function. MATLAB has a simple sort() function that sorts a list of elements in ascending order or descending order based on the condition specified.

The Syntax for sort in Ascending order

The list specified inside the sort function is sorted in an ascending order. We can also specify the dimension alongwith the array we want to sort. It can either be column-wise or row-wise. By default, MATLAB sorts column-wise. We have to specify row wise if we wish to do so. Let’s look at the syntax:

// assume list_num is a list of numbers
Sorted = sort(list_num,dim)

Here, two arguments are given to the sort() function. First is the array or the object we want to sort and the second is the dimension along which we want to sort.

MATLAB uses two dimensions arguments for sorting. If we put dim=1, sorting is done along columns. If we put dim = 2, sorting is done along rows.

One dimensional array/vector

The sort() function can sort one dimensional lists, otherwise known as vectors in MATLAB by simply sorting the row.

Example

one_dimensional = [4 1 5 2 3 9 7];
sorted = sort(one_dimensional)
// answer will be
// [1 2 3 4 5 7 9]

In one dimensional vectors, since there is one column, MATLAB sorts row-wise. We don’t need to specify the dimension here. We can specify the dimension here but it is of no use.

Multi-dimensional rray

The sort() function can sort multi dimensional arrays in MATLAB by sorting the elements column wise. If we wish to do row-wise sorting, we’ll have to specify this.

Example for column-wise sorting

// Column Wise Sorting
matrx = [9 1 3; 
         5 4 2;];
sorted = sort(matrx)
// answer  will be calculated by column-wise sorting
// [ 5 1 2;
//   9 4 3];

Example for row-wise sorting

// Row Wise Sorting
matrx = [9 1 3; 
         5 4 2;];
sorted = sort(matrx,2)
// answer  will be calculated by row-wise sorting
// [ 1 3 9;
//   3 4 5];

Sorting a string array

The MATLAB sort() can further be extended to sort arrays or vectors of strings. As in the case with the numbers, we can sort in both a column-wise and row-wise manner by specifying the dimension. Strings are sorted based on the ASCII value of the first character in ascending order. See the sample below:

//Sorting Column Wise
string_arr = ["Jake" "Harry";
              "Zio"  "Ben";];
sorted = sort(string_arr)
//answer will be
//  ["Jake"    "Ben"  
//   "Zio"     "Harry"]

//Sorting Row Wise
string_arr = ["Jake" "Harry";
              "Zio"  "Ben";];
sorted = sort(string_arr,2)
//answer will be
//  [ "Harry"    "Jake"
//    "Ben"      "Zio" ]

Syntax for sorting in Descending Order

MATLAB allows sorting in descending order. We just have to specify the keyword 'descend' in the code, and the rest is done by MATLAB.

list_arr = [1 4 5 9 6,11];
sorted = sort(list_arr, 'descend')
// answer will be
// [11     9     6     5     4     1]