Return to Answer

replaced http://mathematica.stackexchange.com/ with https://mathematica.stackexchange.com/

Source Link

edited Apr 13, 2017 at 12:56

While Mr.Wizard's f2f2 is fast, there is still faster:

f3[list_, take_, skip_] := 
Pick[list, PadRight[#, Length@list, #]& @ UnitStep @ Range[take - 1, -skip, -1], 1]

on my machine:

Do[f1[a, 3, 2], {100}] // Timing // First
(* 13.023044 *)

Do[f2[a, 3, 2], {100}] // Timing // First
(* 2.665350 *)

Do[f3[a, 3, 2], {100}] // Timing // First
(* 1.461291 *)

While Mr.Wizard's f2 is fast, there is still faster:

f3[list_, take_, skip_] := 
Pick[list, PadRight[#, Length@list, #]& @ UnitStep @ Range[take - 1, -skip, -1], 1]

on my machine:

Do[f1[a, 3, 2], {100}] // Timing // First
(* 13.023044 *)

Do[f2[a, 3, 2], {100}] // Timing // First
(* 2.665350 *)

Do[f3[a, 3, 2], {100}] // Timing // First
(* 1.461291 *)

While Mr.Wizard's f2 is fast, there is still faster:

f3[list_, take_, skip_] := 
Pick[list, PadRight[#, Length@list, #]& @ UnitStep @ Range[take - 1, -skip, -1], 1]

on my machine:

Do[f1[a, 3, 2], {100}] // Timing // First
(* 13.023044 *)

Do[f2[a, 3, 2], {100}] // Timing // First
(* 2.665350 *)

Do[f3[a, 3, 2], {100}] // Timing // First
(* 1.461291 *)

Source Link

created Mar 13, 2013 at 13:46

rcollyer

34.1k
7
94
194

While Mr.Wizard's f2 is fast, there is still faster:

f3[list_, take_, skip_] := 
Pick[list, PadRight[#, Length@list, #]& @ UnitStep @ Range[take - 1, -skip, -1], 1]

on my machine:

Do[f1[a, 3, 2], {100}] // Timing // First
(* 13.023044 *)

Do[f2[a, 3, 2], {100}] // Timing // First
(* 2.665350 *)

Do[f3[a, 3, 2], {100}] // Timing // First
(* 1.461291 *)