Wolfram: List. Add Element

• Insert an element at index n.
• If n is negative, count from right.
• Return a new list.

• Insert

Insert[ {3, 4}, x, 2 ]
(* {3, x, 4} *)

Insert[ {3, 4}, x, -1 ]
(* {3, 4, x} *)

• Insert an element at Position positionSpec

Insert[ {3, {4}}, x, {2,1} ]
(* {3, {x, 4}} *)

insert an element at several positions

Insert[ {{1,0}, {2,0}, {3,0}}, x, {{2}, {3,1}} ]
(* {{1, 0}, x, {2, 0}, {x, 3, 0}} *)

Add to beginning. Return a new expr.

• Prepend

Prepend[ List[ 3, 4 ], 5 ]
(* {5, 3, 4} *)

return a new expr with new item added at end.

• Append

Append[ List[ 3, 4 ], 5 ]
(* {3, 4, 5} *)

Same as x=Prepend[x, new]

• PrependTo

Same as x=Append[x, new]

• AppendTo