TikZ and PGF Manual

The optional foreach part (note that there is no backslash before foreach) allows you to specify multiple children in a single child command. The idea is the following: A \foreach statement is (internally) used to iterate over the list of ⟨values⟩. For each value in this list, a new child is added to the node. The syntax for ⟨variables⟩ and for ⟨values⟩ is the same as for the \foreach statement, see Section 88. For example, when you say

the effect will be the same as if you had said

When you write

the effect will be the same as for

You can nest things as in the following example:

The details and options for this operation are described in the rest of this present section.

This style is used at the beginning of each child, as if you had given the style’s contents as options to the child operation.

If this option is given to a child, the current child counter is increased, but the child is otherwise ignored. In particular, the normal contents of the child is completely ignored.

In the next example, the top and bottom nodes are aligned at the top and the bottom, respectively.

Additional growth functions are defined in the library, see Section 76.

• 1. The following style is executed:

  id="pgf./tikz/edge:from:parent"> /tikz/edge from parent(style, initially draw)

  This style is inserted right before the edge from parent path and before the ⟨options⟩ are inserted.

  

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\begin{tikzpicture}
[edge from parent/.style={draw,red,thick}]
\node {root}
child {node {left} edge from parent[dashed]}
child {node {right}
child {node {child}}
child {node {child} edge from parent[draw=none]}
};
\end{tikzpicture}


• 2. Next, the ⟨options⟩ are executed.

• 3. Next, the text stored in the following key is inserted:

  id="pgf./tikz/edge:from:parent:path"> /tikz/edge from parent path=⟨path⟩ (no default, initially code shown below) ¶

  This option allows you to set the edge from parent path to a new path. Initially, this path is the following:

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(\tikzparentnode\tikzparentanchor) -- (\tikzchildnode\tikzchildanchor)


  The \tikzparentnode is a macro that will expand to the name of the parent node. This works even when you have not assigned a name to the parent node, in this case an internal name is automatically generated. The \tikzchildnode is a macro that expands to the name of the child node. The two ...anchor macros are empty by default. So, what is essentially inserted is just the path segment (\tikzparentnode) -- (\tikzchildnode); which is exactly an edge from the parent to the child.

  You can modify this edge from parent path to achieve all sorts of effects. For example, we could replace the straight line by a curve as follows:

  

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\begin{tikzpicture}[level distance=15mm, sibling distance=15mm,
edge from parent path=
{(\tikzparentnode.south) .. controls +(0,-1) and +(0,1)
.. (\tikzchildnode.north)}]
\node {root}
child {node {left}}
child {node {right}
child {node {child}}
child {node {child}}
};
\end{tikzpicture}


  Further useful edge from parent paths are defined in the tree library, see Section 76.

  The nodes in a ⟨node specification⟩ following the edge from parent path command get executed as if the pos option had been added to all these nodes, see also Section 17.8.

  As an example, consider the following code:

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\node (root) {} child {node (child) {} edge to parent node {label}};


  The edge to parent operation and the following node operation will, together, have the same effect as if we had said:

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(root) -- (child) node [pos=0.5] {label}


  Here is a more complicated example:

  

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\begin{tikzpicture}
\node {root}
child {
node {left}
edge from parent
node[left] {a}
node[right] {b}
}
child {
node {right}
child {
node {child}
edge from parent
node[left] {c}
}
child {node {child}}
edge from parent
node[near end] {x}
};
\end{tikzpicture}


  As said before, the anchors in the default edge from parent path are empty. However, you can set them using the following keys:

  id="pgf./tikz/child:anchor"> /tikz/child anchor=⟨anchor⟩ (no default, initially border) ¶

  Specifies the anchor where the edge from parent meets the child node by setting the macro \tikzchildanchor to .⟨anchor⟩.

  If you specify border as the ⟨anchor⟩, then the macro \tikzchildanchor is set to the empty string. The effect of this is that the edge from the parent will meet the child on the border at an automatically calculated position.

  

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\begin{tikzpicture}
\node {root}
[child anchor=north]
child {node {left} edge from parent[dashed]}
child {node {right}
child {node {child}}
child {node {child} edge from parent[draw=none]}
};
\end{tikzpicture}


  /tikz/parent anchor=⟨anchor⟩ (no default, initially border) ¶

  This option works the same way as the child anchor, only for the parent.

All of the above describes the standard functioning of the edge from parent command. You may, however, sometimes need even more fine-grained control (the graph drawing engine needs it, for instance). In such cases the following key gives you complete control: