This is my list

Matrix = {{1, -2, 3, -4}, {{a, b}, {f, e}, {a, b}, {f, e}}}

I want to order the columns in ascending order depending on the values on the first row. I Expect something like

{{-4, -2, 1, 3}, {{f, e}, {f, e}, {a, b}, {a, b}}}

I've tried the Sort function, but it just returns the initial value

up vote 6 down vote accepted
Transpose[SortBy[Transpose[Matrix], First]]

{{-4, -2, 1, 3}, {{f, e}, {f, e}, {a, b}, {a, b}}}

Transpose[Transpose[#][[Ordering @ First @ #]]] &@ Matrix

{{-4, -2, 1, 3}, {{f, e}, {f, e}, {a, b}, {a, b}}}

Renaming Matrix to myMatrix (so as to avoid starting a variable name with an upper-case letter):

 SortBy[Table[{myMatrix[[1, i]], myMatrix[[2, i]]}, 
   {i, 4}], #[[1]] &]]
  • Perhaps, you meant Matrix instead of myMatrix. – bbgodfrey Oct 18 at 0:12
  • 1
    Yes... in my personal code I changed the name because we must never use an upper-case letter to start the name of a variable, lest it conflict with internal definitions. Thanks. Solution amended. – David G. Stork Oct 18 at 0:15

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