Matlab Functions - sort

sort

• B = sort(A,<dim>,<dir>) sorts the elements of A along dimension dim

  • dir sets the sort direction; valid values are 'ascend' or 'descend', defaulting to ascending ('ascend')

  • dim must be an integer; it defaults to the first non-singleton dimension

  • “Along dimension dim” means (for the ascending case):

$\begin{aligned} \bm{A}(x_1,\underset{dim\text{th arg}}{\cdots,1,\cdots},x_n) &\leq \bm{A}(x_1,\underset{dim\text{th arg}}{\cdots,2,\cdots},x_n)\\ & \leq \cdots\\ & \leq \bm{A}(x_1,\underset{dim\text{th arg}}{\cdots,end,\cdots},x_n) \end{aligned}

• Special cases:
  • If A is a vector, sort(A) sorts the elements of the vector
  • If A is a matrix, sort(A) treats each column of A as a vector and sorts each column
  • If A is a matrix, sort(A,2) sorts the elements of each row

- `B = sort(___,Name,Value)` specifies additional sort parameters - For example, `sort(A,'ComparisonMethod','abs')` sorts the elements of _A_ by magnitude - `[B,I] = sort(___)` - _I_ is the **index array** describing how _A_ was rearranged - For a vector, `B = A(I)` - For higher-dimensional arrays, recovering the sorted array from _I_ alone requires a more involved indexing pattern