BUILT-IN MATHEMATICA SYMBOL

# Part

or Part[expr, i]
gives the i part of expr.

counts from the end.

or Part[expr, i, j, ...]
is equivalent to .

gives a list of the parts , , ... of expr.

gives parts m through n.

gives parts m through n in steps of s.

## DetailsDetails

• You can make an assignment like 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, 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 . Each part has one index from each list.
• If any of the are All or , all parts at that level are kept.
• Notice that lists are used differently in Part than in functions like Extract, MapAt, and Position.
• If expr is a SparseArray object, gives the parts in the corresponding ordinary array. »
• In StandardForm and InputForm, can be input as .
• and can be entered as Esc[[Esc and Esc]]Esc or \[LeftDoubleBracket] and \[RightDoubleBracket].
• In StandardForm, can be input as or .

## ExamplesExamplesopen allclose all

### Basic Examples (10)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=