is an option for Tree and related functions that specifies a function to use to generate edge labels.


  • ParentEdgeLabelFunction allows specifying the function to generate the label of the parent edge of the root node of a tree, as well as that of any subtrees at positions matching a pattern.
  • The following option settings can be used:
  • Automaticuse the keys of associations as the labels
    Noneuse no label
    funca general edge label function
    {pos1func1,pos2func2,}use edge label function funci at position posi
    {patt1func1,patt2func2,}use funci at positions matching patti
  • Edge label specifications are effectively applied in the order ParentEdgeLabel, ParentEdgeLabelStyle and ParentEdgeLabelFunction, with later specifications overriding earlier ones.
  • ParentEdgeLabelFunctionfunc specifies that the label of the parent edge of the root node should be provided by func[data], where data is the data in the root.
  • In ParentEdgeLabelFunction, Allfunc uses func for all subtrees.
  • In ParentEdgeLabelFunction, TreeCases[pattern]func uses func for all subtrees with data matching pattern.


open allclose all

Basic Examples  (4)

Label an individual edge:

Label all subtree elements:

Use no labels:

Specify positions using position patterns:

Specify positions using data patterns:

Properties & Relations  (5)

Edges are automatically labeled with the keys of an association of children:

No labels are used for a list of children:

Labels for edges can be specified by position:

Labels specified by a subtree take precedence over labels specified by its ancestors:

A position {i,j,} in a subtree refers to its subtree at relative position {i,j,}:

A relative position {2} at position {1} refers to the global position {1,2}:

In general, a pattern patt applies to subtrees at global positions {i,j,} that match patt:

A list of patterns {patt1,patt2,} applies to relative positions {i,j,} that match the patti:

Wolfram Research (2022), ParentEdgeLabelFunction, Wolfram Language function,


Wolfram Research (2022), ParentEdgeLabelFunction, Wolfram Language function,


Wolfram Language. 2022. "ParentEdgeLabelFunction." Wolfram Language & System Documentation Center. Wolfram Research.


Wolfram Language. (2022). ParentEdgeLabelFunction. Wolfram Language & System Documentation Center. Retrieved from


@misc{reference.wolfram_2024_parentedgelabelfunction, author="Wolfram Research", title="{ParentEdgeLabelFunction}", year="2022", howpublished="\url{}", note=[Accessed: 23-July-2024 ]}


@online{reference.wolfram_2024_parentedgelabelfunction, organization={Wolfram Research}, title={ParentEdgeLabelFunction}, year={2022}, url={}, note=[Accessed: 23-July-2024 ]}