graphicstikz-pgftrees
clarification: when I say "graph", I mean the computer science term.
I want to draw a full binary tree of h height. It means that there's one root with two sons, each son has two sons and so forth.
Is there a way to make LaTeX (with tikZ for example, but any other way will do) draw a full binary tree of a given h height without manually drawing each node? This should also allow me to write on the edges and on the leaves.
Thanks.
Deep in the bowels of TikZ, the child creation code calls \foreach to create the children. However, by the time it has done so then the various parameters to the \foreach loop have passed through several macros. Each time, there is the potentiality to strip off an outer pair of braces. Rather than try to keep track of this, TikZ gets round it by ensuring that the inner call to \foreach is of the form \foreach#2in{#3} which means that in your situation it sees \foreach \x in {\xs}. This is what is preventing the \foreach from expanding the macro to find the list: if it saw \foreach \x in \xs there would be no problem.
So we need to hack the code. When the foreach is first noticed we need to peek ahead to see if the range is surrounded by braces or not and remember that for when we get to the bottom. There are probably far more elegant ways of doing this than the following which involves a reasonable amount of repeated code (I copied the places where TikZ has the \foreach and removed the braces and then put in a decision as to which set of macros to use at the outset).
\documentclass{article}
%\url{http://tex.stackexchange.com/q/67187/86}
\usepackage{tikz}
\makeatletter
\def\tikz@collect@children@foreach[#1]foreach#2in{%
\pgfutil@ifnextchar\bgroup{\tikz@collect@children@foreachbr{#1}{#2}}%
{\tikz@collect@children@foreachnbr{#1}{#2}}}
\def\tikz@collect@children@foreachbr#1#2#3{%
\pgfutil@ifnextchar\bgroup{\tikz@collect@children@foreachA{#1}{#2}{#3}}{\tikz@collect@children@foreachA{#1}{#2}{#3}{}}}
\def\tikz@collect@children@foreachnbr#1#2#3{%
\pgfutil@ifnextchar\bgroup{\tikz@collect@children@foreachAnbr{#1}{#2}{#3}}{\tikz@collect@children@foreachAnbr{#1}{#2}{#3}{}}}
\def\tikz@collect@children@foreachAnbr#1#2#3#4{%
\expandafter\def\expandafter\tikz@children@list\expandafter
{\tikz@children@list\tikz@childrennodesnbr[#1]{#2}{#3}{#4}}%
\c@pgf@counta=\tikznumberofchildren%
\foreach#2in#3%
{%
\global\advance\c@pgf@counta by1\relax%
}%
\tikznumberofchildren=\c@pgf@counta%
\tikz@collect@children%
}
\def\tikz@childrennodesnbr[#1]#2#3#4{%
\c@pgf@counta=\tikznumberofcurrentchild\relax%
\setbox\tikz@tempbox=\box\tikz@figbox%
\foreach#2in#3{%
\tikznumberofcurrentchild=\c@pgf@counta\relax%
\setbox\tikz@figbox=\box\tikz@tempbox%
\tikz@childnode[#1]{#4}%
% we must now make the current child number and the figbox survive
% the group
\global\c@pgf@counta=\tikznumberofcurrentchild\relax%
\global\setbox\tikz@tempbox=\box\tikz@figbox%
}%
\tikznumberofcurrentchild=\c@pgf@counta\relax%
\setbox\tikz@figbox=\box\tikz@tempbox%
}
\makeatother
\begin{document}
\begin{tikzpicture}
\node at (5cm,0) {root} [level/.append style={sibling distance=2cm/#1}]
child foreach \xs in {{A,B}, {C,D}} {
coordinate
child foreach \x in \xs {
node {\x}}};
\end{tikzpicture}
\end{document}
Produces:
Have you tried something like node[pos=xx]?
\documentclass{standalone}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}
\draw[<->,rotate around={22.5:(0,0)}]
(0,1) --(0,0.2) node[pos=-0.2] {$y$}
-- (1,0.2) node[pos=1.2] {$x$};
\end{tikzpicture}
\end{document}
The pos key of a node places it that position along the segment. pos=0 is the beginning, and pos=1 is the end. pos=0.5 is the middle, sometimes useful, but not here.
We need to place the nodes a little bit before the beginning of the segment and a little bit after. So we subtract a little bit from 0 and add a little bit to 1.
The disadvantage here is that the separation you get is as a fraction of the segment length. So if you want a fixed distance from the end you may need to find another way.
Best Answer
Here's an admittedly hackish solution I just whipped up using TikZ:
You'll have to tweak it a bit to get the desired spacing between nodes.
Just stick that code that the top of your document (or in a new
.sty). Then you can use it like this:The edges and leaves are indexed according to their order in the tree's associated Ahnentafel list. The result should look like this: