Wolfram: Flatten

By Xah Lee. Date: .

Flatten

Flatten
  • Flatten[ list]
  • Flatten[ list, n]
  • Flatten[ list, n, h ]

flatten a list, up to level n (default Infinity), and only those with Head h (default List)

Flatten[ {3, {9, {4}}, 5} ]
(* {3, 9, 4, 5} *)

Flatten[ {3, {9, {4}}, 5}, 1 ]
(* {3, 9, {4}, 5} *)

Flatten[ {3, {9, {4}}, 5}, 2 ]
(* {3, 9, 4, 5} *)

(* flatten only those with head f *)
Flatten[ {3, f[9, {4}], g[5]}, Infinity, f ]
(* {3, 9, {4}, g[5]} *)