Lining up leaf nodes in pstree

Question

I am a TeX newbie, trying to make a syntax tree. What I'm going for is this:

        X
       /           X            / \           X   \          / \   \         X   \   \        / \   \   \       A   B   C   D   E
a   b   c   d   e

where the bottom row includes some subscripts. My code is as follows:

\pstree[levelsep=5ex]{ \TR{X} }{
  \pstree{ \TR{X} }{
    \pstree{ \TR{X} }{
      \pstree{ \TR{X} }{
        \TR{\shortstack{{\em A}\\a}}
        \TR{\shortstack{{\em B}\\b}}
      }
      \TR{\shortstack{{\em C}\\c}}
    }
    \TR{\shortstack{{\em D}\\d}}
  }
  \TR{\shortstack{{\em E}\\e}}
}

Two questions:

a) How can I align the leaf nodes at the bottom instead of immediately beneath their mother node?

b) The vertical spacing of the things in the shortstack is inconsistent (probably by some sort of "if it fits" criterion - if if there's an "j" or a "g" on the upper word, the spacing increases to accomodate the downstroke). Is there a better way of writing things one beneath another that will always have the same vertical spacing?

EDIT: as requested, minimal example of node-internal formatting problem:

\pstree[levelsep=5ex]{ \TR{Compare:} }{
  \TR{\shortstack{h\\j}}
  \TR{\shortstack{m\\n}}
}

Notice how higher "h" is compared to "m" ("j" and "n" being level).

See if this question helps you: How to draw syntactical trees with parallel leafs for a natural language?. Unless you must use pstricks for independent reasons, I recommend using tikz-qtree for this. — Alan Munn, Oct 24 '11 at 16:56
Dunno, I couldn't get in-node formatting to work in tikz-qtree. Besides, this is almost good-enough (if it only weren't for the damn shortstack spacing problems) — Amadan, Oct 24 '11 at 19:09
I guess the question is how you want the tree to look. As you have more nodes and if the tree has right hand nodes that themselves branch, having the branches project directly to the terminals makes for a very large tree. If the example in my answer to the linked question is a satisfactory way to represent the terminal nodes, edit your question to show a minimal example of the problem you are having with the in-node formatting, and maybe we can solve that. — Alan Munn, Oct 24 '11 at 19:23
@Amadan: See my answer to correct for this vertical misalignment. — Werner, Oct 24 '11 at 19:42
@Amadan I was expecting a tikz-qtree example (based on your previous comment about not getting it to work.) — Alan Munn, Oct 24 '11 at 19:43
@AlanMunn: Oh, sorry. Misunderstood. I don't remember what didn't work any more, just that I tried and failed. And Werner's example works like a charm, without me having to rewrite all my examples into a different form. — Amadan, Oct 24 '11 at 22:48
@Amadan That's fine. Werner's solution is indeed very nice. It's always interesting to see the neat things that makes pstricks live up to its name. — Alan Munn, Oct 24 '11 at 23:24

score 4 · Answer 1 · answered Oct 24 '11 at 18:15

Do you mean something like skiplevel?

\documentclass{article}
\usepackage{pst-tree}
\begin{document}

\pstree[treesep=1.2cm,levelsep=0.5cm]{ \TR{X} }{
  \pstree{ \TR{X} }{
    \pstree{ \TR{X} }{
      \pstree{ \TR{X} }{
        \TR{\shortstack{{\em A}\\a}}
        \TR{\shortstack{{\em B}\\b}}
      }
      \skiplevels{1}%\skiplevel{\Tn\Tn}
        \TR{\shortstack{{\em C}\\c}}
      \endskiplevels
      }
      \skiplevels{2}%\skiplevel{\Tn\Tn}
            \TR{\shortstack{{\em D}\\d}}
      \endskiplevels
    }
    \skiplevels{3}%\skiplevel{\Tn\Tn}
        \TR{\shortstack{{\em E}\\e}}
    \endskiplevels
  }
\end{document}

Werner · Accepted Answer · 2011-10-24T20:37:39.070

Using \skiplevel{...} or \skiplevels{<num>}...\endskiplevels you can push nodes down a (or <num>) level(s) to line them up with nodes on a lower level. The projection is such that it keeps the horizontal alignment as if the nodes were on their original level.

Additionally, instead of using \substack, you could add the contents in a tabular like in the macro \stackit{<top>}{<bottom>} below. It places <top> and <bottom> in a tabular (aligned at the top [t]) with center alignment (and no inter-column spacing @{} on either side). Additionally, <top> is typeset using emphasize {\em ..}. All the baselines will be vertically aligned. If you have a more complex arrangement of leave node labels, then other alternatives also exist:

enter image description here

\documentclass{article}
\usepackage{pst-tree}% http://ctan.org/pkg/pst-tree
% A macro to stack leave node contents: \stackit{<top>}{<bottom>}
\newcommand{\stackit}[2]{\begin{tabular}[t]{@{}c@{}}{\em #1}\\#2\end{tabular}}
\begin{document}
\pstree[levelsep=5ex,nodesep=3pt]{ \TR{X} }{
  \pstree{ \TR{X} }{
    \pstree{ \TR{X} }{
      \pstree{ \TR{X} }{
        \TR{\stackit{A}{a}}
        \TR{\stackit{B}{b}}
      }
      \skiplevel{\TR{\stackit{C}{c}}}
    }
    \skiplevels{2}\TR{\stackit{D}{d}}\endskiplevels
  }
  \skiplevels{3}\TR{\stackit{E}{e}}\endskiplevels
}
\end{document}

Oooh, tabular works great! Although renewcommand fails with LaTeX Error: \stackit undefined.... Works with newcommand though. Weird. Anyway - thank you! — Amadan, Oct 24 '11 at 19:42
Sorry, corrected the code now - \renewcommand is only used if the macro already exists. If not, use \newcommand. \providecommand would also have worked, which executes either \renew... or \new... based on the existence of the command. — Werner, Oct 24 '11 at 19:45

score 0 · Answer 3 · answered Oct 24 '11 at 19:59

\documentclass{article}
\usepackage{pst-tree}
\newcommand\Stack[2][0.8]{{\def\arraystretch{#1}\tabular{@{}c@{}}#2\endtabular}}
\begin{document}

\pstree[levelsep=10mm,nodesep=1mm]{ \TR{X} }{
  \pstree[]{ \TR{X} }{
    \pstree{ \TR{X} }{
      \pstree[treesep=5mm]{ \TR{X} }{
        \TR{\Stack{\em A\\a}}
        \Tn
        \TR{\Stack{\em B\\b}}
        \Tn
      }
      \skiplevel{\TR{\Stack{\em C\\c}}}
    }
    \skiplevels{2}\TR{\Stack{\em D\\d}}\endskiplevels
  }
  \skiplevels{3}\TR{\Stack{\em E\\e}}\endskiplevels
}
\end{document}

enter image description here

Lining up leaf nodes in pstree

3 Answers3