# TreeCount

TreeCount[tree,pattern]

gives the number of subtrees of tree whose data matches pattern.

TreeCount[tree,pattern,levelspec]

gives the total number of subtrees with data matching pattern that appear at the levels in tree specified by levelspec.

TreeCount[pattern]

represents an operator form of TreeCount that can be applied to a tree.

# Details • TreeCount gives the number of subtrees with data matching any pattern on any range of levels in a Tree object.
• TreeCount uses standard level specifications as in TreeLevel:
•  n levels 1 through n All levels 0 through Infinity Infinity levels 1 through Infinity {n} level n only {n1,n2} levels n1 through n2
• The default value for levelspec in TreeCount is {0,Infinity}.
• A positive level n+1 consists of all subtrees of tree that are children of subtrees on level n.
• Level 0 corresponds to the root of the tree.
• Level -1 corresponds to the leaves.
• A negative level -(n+1) consists of all subtrees whose children are on levels -1, -2, , -n, with highest level -n.
• TreeCount traverses subtrees in a left-to-right, depth-first order, with children visited before their parents.
• TreeCount[pattern][tree] is equivalent to TreeCount[tree,pattern].

# Examples

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## Basic Examples(3)

Count the number of subtrees whose data is an even number:

Count the inner subtrees whose data is an even number:

Use the operator form of TreeCount:

## Scope(5)

Count the subtrees whose data is an odd integer:

Count the subtrees at levels 1 and 2 whose data is an odd integer:

Count the leaf subtrees whose data is an odd integer:

Count the inner subtrees whose data is an odd integer:

Use the operator form of TreeCount:

## Properties & Relations(4)

TreeCount gives the number of matching subtrees given by TreeCases:

TreeSize[tree] is equivalent to TreeCount[tree,_]:

Count[expr,pattern,levelspec] is equivalent to TreeCount[ExpressionTree[expr,"Subexpressions"],pattern,levelspec]: