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BUILT-IN MATHEMATICA SYMBOL

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Position

gives a list of the positions at which objects matching pattern appear in expr.

Position

finds only objects that appear on levels specified by levelspec.

Position

gives the positions of the first n objects found.

MORE INFORMATION

Position tests all the subparts of expr in turn to try and find ones that match pattern.

Position returns a list of positions in a form suitable for use in Extract, ReplacePart, and MapAt. The form is different from the one used in Part.

The default level specification for Position is {0, Infinity}, with Heads->True.

A part specification returned by Position represents the whole of expr.

Position[list, pattern, {1}, Heads->False] finds positions only of objects that appear as complete elements of list.

Position uses standard level specifications:

	n	levels through n
	Infinity	levels through Infinity
	{n}	level n only
	{n₁,n₂}	levels through

A positive level n consists of all parts of expr specified by n indices.

A negative level -n consists of all parts of expr with depth n.

Level corresponds to the whole expression.

With the default option setting Heads->True, Position includes heads of expressions, and their parts.

Position traverses expressions in depth-first order, yielding lists of indices in lexicographic order.

EXAMPLES

CLOSE ALL

Basic Examples (2)

Find the positions at which

occurs:

Find all positions at which

to any power appears:

Find only those down to level 2:

Find the positions at which

occurs:

In[1]:=

Out[1]=

In[2]:=

Out[2]=

Find all positions at which

to any power appears:

In[1]:=

Out[1]=

Find only those down to level 2:

In[2]:=

Out[2]=

Scope (2)

Find the positions of the first 2

's that appear on level 1:

Depth-first traversal gives longer lists of indices first:

Generalizations & Extensions (1)

Position works with any head, not just List:

Options (1)

Properties & Relations (1)

Use Extract to extract parts based on results from Position:

Possible Issues (1)