# tree (sequence) diagram in Asymptote

I want to draw tree diagram with Asymptote. But have some problems.

I searched and found 2 hints on the web. http://asymptote.sourceforge.net/FAQ/section4.html http://asymptote.sourceforge.net/doc/Frames-and-pictures.html

Using theese tips, and tried to box and trees.

settings.outformat="pdf";
unitsize(5cm);

usepackage(amsmath);

frame f1;
label(f1, "$\mathbb{N} \models A(0)$", Draw);
add(f1, (0, 5))

frame f2;
label(f2, "$\mathbb{N} \models A(1)$", Draw);
add(f2, (0, 4));

draw(f1 -- f2);


But this doesn't work. Last draw(f1 -- f2); command is wrong.

draw commands need coordinate. But this method is... not smart (for me).

I want to connect 2 boxes. How Can I connect 2 objects?

I found drawtree module in the official tutorials PDF, but it looks difficult to use flexibly(is tree's shape changeable?).

If there is a way of easily using drawtree module, would you tell that?

Thanks.

• Welcome to TeX.SX! You can have a look at our starter guide to familiarize yourself further with our format. – Seamus Feb 11 '16 at 10:00
• I find the graph theory module good for this kind of thing. Documentation could be better, but the functionality works for me. github.com/taoari/asy-graphtheory – Jim Hefferon Feb 11 '16 at 12:40
• Links are good! – kogemochi Feb 18 '16 at 7:24

## 2 Answers

The following code works as a standalone asymptote script. I haven't used the drawtree module so I can't help you with that. In my code, I am not using frames. Instead, each label is drawn in the default picture.

texpreamble("\usepackage{amssymb}");
settings.outformat="pdf";
unitsize(5cm);

pair p1 = (0, 5);
pair p2 = (0, 4);

draw(p1--p2);

label("$\mathbb{N} \models A(0)$", p1, FillDraw(white, black));
label("$\mathbb{N} \models A(1)$", p2, FillDraw(white, black)); • Your method is simple and useful! Thank you!But I have an another problem. – kogemochi Feb 17 '16 at 10:59
• When I change draw(p1--p2) to draw(p1--p2, arrow=Arrow), arrow is not displayed. If the second label is not present, the arrow can be seen. Do you have a solution? – kogemochi Feb 17 '16 at 11:09
• @kogemochi: The line extends to the middle of the label, so the arrow head is filled over when the label is drawn. The easiest solution might be to use MidArrow instead. – James Feb 17 '16 at 13:44
• Getting your hint, searched further, draw(p1--p2, arrow=Arrow(position=0.945)) was found. It looks nice for me. Options are difficult... – kogemochi Feb 18 '16 at 7:17

Since alternative methodologies are generally acceptable, I cannot resist providing a forest solution.

math content puts the content of all nodes in maths mode, avoiding the need for $...$. draw draws a border around each node in the tree.

The nodes are automatically connected: parent to child for each parent-child relationship. (Use <node content>, no edge for exceptions.) I've specified l sep to match the unit defined in the original code. This is the minimum distance between levels of the tree. (5cm is a lot.)

forest does not need explicit coordinates. It will automatically format the tree.

\documentclass[tikz, border=10pt, multi]{standalone}
\usepackage{forest,amssymb}
\begin{document}
\begin{forest}
for tree={
draw,
math content,
l sep=50mm,
}
[\mathbb{N} \models A(0)
[\mathbb{N} \models A(1)]
]
\end{forest}
\end{document} To alter the appearance of the tree is very easy. You just alter the preamble of the forest environment.

For example,

   for tree={
draw=red,
thick,
edge={blue, thick, <->},
fill=red!10,
math content,
l sep=50mm,
grow=45,
}


produces while the specification for the tree itself remains identical

  [\mathbb{N} \models A(0)
[\mathbb{N} \models A(1)]
]

• I didn't know well about tikz. Thank you. – kogemochi Feb 17 '16 at 11:29