Wolfram: List. Get Element by Index (Part, Take, Drop, First, Last, Most, Rest)

By Xah Lee. Date: 2022-07-04. Last updated: 2025-12-26.

Get Item by Index

Get a Single Item by Index

Part[expr, i]

🔸 SHORT SYNTAX: expr[[i]]

ith part of expr. If i is negative, count from right.

Part

Part[{a, b, c, {d1, d2}, e}, 2]
(* b *)

(* short syntax *)
{a, b, c, {d1, d2}, e}[[2]]
(* b *)

(* count from right *)
{a, b, c, {d1, d2}, e}[[-2]]
(* {d1, d2} *)

Get Multiple Items by Multiple Indexes

Part[expr, {a, b, c}]

🔸 SHORT SYNTAX: expr[[{a, b, c}]]

Same as { Part[expr, a], Part[expr, b], Part[expr, c] }

{a, b, c, {d1, d2}, e}[[{2,-1}]]

(* {b, e} *)

Get Nested Item by Indexes

Part[expr, a, b, c]

🔸 SHORT SYNTAX: expr[[a, b, c]]

same as Part[Part[Part[expr, a], b], c]

same as Extract[expr, {a,b,c} ]

Wolfram: Extract (Get Element by Position)

{a, b, c, {d1, d2}, e}[[4,1]]
(* d1 *)

Extract[{a, b, c, {d1, d2}, e}, {4,1}]
(* d1 *)

Get a range of Items by Index Range

Part[expr, m;;n]

🔸 SHORT SYNTAX: expr[[m;;n]]

(note: a;;b is short for Span[a, b])

parts m through n. If m is omitted, default to beginning. If n is omitted, default to end.

{a, b, c, {d1, d2}, e}[[2;;4]]

(* {b, c, {d1, d2}} *)

expr[[m;;]] → part m to end
expr[[;;n]] → beginning to n
expr[[;;,j]] → column j
expr[[m1;;n1, m2;;n2]] → submatrix

(* column 1 *)
{{a,b}, {c,d}}[[;;,1]]

(* {a, c} *)

Get Items by Range of Index

Take

take nth to mth item

Take

(* basic examples of Take *)

(* First 3 *)
Take[{1, 2, 3, 4, 5, 6, 7, 8, 9}, 3]
(* {1, 2, 3} *)

(* last 3 *)
Take[{1, 2, 3, 4, 5, 6, 7, 8, 9},-3]
(* {7, 8, 9} *)

(* m to n *)
Take[{1, 2, 3, 4, 5, 6, 7, 8, 9}, {3,5}]
(* {3, 4, 5} *)

Drop