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sortcols

sortcols(A, [alg=,] [by=,] [lt=,] [rev=false])

Sort the columns of matrix A lexicographically.

Examples

1. Sort columns lexicographically:

   julia> A = [4 3 2; 1 2 3; 3 1 4];
   julia> sortcols(A)
   3×3 Array{Int64,2}:
   1  2  3
   3  1  4
   4  3  2

   This example sorts the columns of matrix A in lexicographic order.

2. Sort columns with a custom comparison function:

   julia> A = [4 3 2; 1 2 3; 3 1 4];
   julia> sortcols(A, lt=by(x -> x % 3))
   3×3 Array{Int64,2}:
   4  3  2
   1  2  3
   3  1  4

   The lt argument specifies a custom comparison function. In this example, the columns are sorted based on the remainder of each element divided by 3.

3. Sort columns in reverse order:

   julia> A = [4 3 2; 1 2 3; 3 1 4];
   julia> sortcols(A, rev=true)
   3×3 Array{Int64,2}:
   2  3  4
   3  2  1
   4  1  3

   By setting rev to true, the columns are sorted in reverse order.

Common mistake example:

julia> A = [4 3 2; 1 2 3; 3 1 4];
julia> sortcols(A, by=abs)
ERROR: MethodError: no method matching abs(::Array{Int64,2})

In this example, the by argument is used incorrectly. abs is a function that operates on individual elements, not on the entire array. Make sure to provide a valid transformation function that can be applied to each column.

See Also

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