This is documentation for Mathematica 6, which was
based on an earlier version of the Wolfram Language.

# Part ([[...]])

 expr[[i]] or Part[expr, i]gives the i part of expr. expr[[-i]]counts from the end. expr[[i, j, ...]] or Part[expr, i, j, ...]is equivalent to expr[[i]][[j]].... expr[[{i1, i2, ...}]]gives a list of the parts i1, i2, ... of expr. expr[[m;;n]] gives parts m through n. expr[[m;;n;;s]] gives parts m through n in steps of s.
• You can make an assignment like t[[spec]]=value to modify any part or sequence of parts in an expression.  »
• Part 0 of an expression is its head.
• Common spans of parts include:
 expr[[m;;]] part m through the end expr[[;;n]] from the beginning to part n expr[[;;,j]] column j expr[[m1;;n1,m2;;n2]] submatrix
• When expr is a list, expr[[{i1, i2, ...}]] gives a list of parts. In general, the head of expr is applied to the list of parts.  »
• You can get a nested list of parts from expr[[list1, list2, ...]]. Each part has one index from each list.
• If any of the listi are All or ;;, all parts at that level are kept.
• If expr is a SparseArray object, expr[[...]] gives the parts in the corresponding ordinary array.  »
• and can be entered as Esc [[ Esc and Esc ]] Esc or \[LeftDoubleBracket] and \[RightDoubleBracket].
• In StandardForm, expr[[spec]] can be input as expr[[spec]] or exprspec.
 Basic Examples   (10)
Pick out a part of a list:
 Out[1]=

Pick out a sequence of parts:
 Out[1]=

Pick out a part of a matrix:
 Out[1]=

The second row of a matrix:
 Out[1]=

The second column of a matrix:
 Out[1]=

An element 2 from the end of a list:
 Out[1]=

A list of parts:
 Out[1]=

Reassign a part:
 Out[1]=
 Out[2]=
 Out[3]=

Reassign a sequence of parts:
 Out[1]=
 Out[2]=
 Out[3]=

Part works with expressions of any kind, not just lists:
 Out[1]=
 Out[2]=
 Out[3]=
Part always operates on the FullForm of expressions:
 Out[4]=
 Out[5]//FullForm=
 Scope   (10)
 Applications   (4)