sortc, sortcc

Purpose

Sorts a numeric matrix, character matrix or string array.

Format

y = sortc(x, c)
y = sortcc(x, c)
Parameters:
  • x (NxK matrix or string array.) – data
  • c (scalar) – specifies the column of x to sort on
Returns:

y (NxK matrix) – equal to x and sorted on the column c.

Examples

Sort rows of a matrix based upon first column

x = { 4 7 3,
      1 3 2,
      3 4 8 };

// Sort 'x' based upon the first row
y = sortc(x, 1);

The above example code produces, y equal to:

1 3 2
3 4 8
4 7 3

Sort rows of a 5x1 string vector

// Create a 5x1 string array, using the string
// vertical concatenation operator '$|'
letters = "epsilon" $|
          "gamma" $|
          "beta" $|
          "alpha" $|
          "delta";

// Sort 'letters'
letters_s = sortc(letters, 1);

The above example code produces, letters_s equal to:

  alpha
   beta
  delta
epsilon
  gamma

Remarks

  • These functions will sort the rows of a matrix with respect to a specified column. That is, they will sort the elements of a column and will arrange all rows of the matrix in the same order as the sorted column.

  • sortc() assumes that the column to sort on is numeric. sortcc() assumes that the column to sort on contains character data.

  • The matrix may contain both character and numeric data, but the sort column must be all of one type.

  • Missing values will sort as if their value is below \(-\infty\).

  • The sort will be in ascending order.

  • This function uses the Quicksort algorithm.

  • If you need to obtain the matrix sorted in descending order, you can use:

    rev(sortc(x, c))
    

See also

Functions rev(), sortind(), unique()