forest-decisiontree.sty

\ProvidesPackage{forest-decisiontree}[2013/01/20]
\RequirePackage{forest}[2013/01/20]

\def\getfirst#1;#2\endget{\unexpanded{#1}}
\def\getsecond#1;#2\endget{\unexpanded{#2}}
\forestset{
  declare toks={decision}{},
  declare keylist={decision options}{midway},
  anchors/.style={anchor=#1,child anchor=#1,parent anchor=#1},
  nomath/.style={content format=\forestoption{content}},
  dot/.style={tikz+={\fill (.child anchor) circle[radius=#1];}},
  dot/.default=2pt,
  decision on left/.style={decision options={auto=left,anchor=east}},
  decision on right/.style={decision options={auto=left,anchor=west}},
  decision tree/.style n args=3{
    anchors=south, outer sep=2pt,
    for tree={
      s sep=#1,l=#2,dot=#3,
      if n children=0{anchors=north}{
        if n=1{anchors=south east}{anchors=south west}},
      content format={$\forestoption{content}$},
      if n=1{decision on left}{decision on right}
    },
    delay={for descendants={
        decision/.expanded/.wrap pgfmath arg={\getsecond##1\endget}{content},
        content/.expanded/.wrap pgfmath arg={\getfirst##1\endget}{content},
    }},
    before drawing tree={
      for descendants={
        edge label/.expanded={node[\forestoption{decision options}]{\strut$\forestoption{decision}$}},
      }
    }
  },
  decision tree/.default={0.5em}{8ex}{2pt}
}