\section{Tree\+Traits$<$ Tree\+Type $>$ Class Template Reference} \label{classmlpack_1_1tree_1_1TreeTraits}\index{Tree\+Traits$<$ Tree\+Type $>$@{Tree\+Traits$<$ Tree\+Type $>$}} The \doxyref{Tree\+Traits}{p.}{classmlpack_1_1tree_1_1TreeTraits} class provides compile-\/time information on the characteristics of a given tree type. \subsection*{Static Public Attributes} \begin{DoxyCompactItemize} \item static const bool \textbf{ Binary\+Tree} = false \begin{DoxyCompactList}\small\item\em This is true if the tree always has only two children. \end{DoxyCompactList}\item static const bool \textbf{ First\+Point\+Is\+Centroid} = false \begin{DoxyCompactList}\small\item\em This is true if the first point of each node is the centroid of its bound. \end{DoxyCompactList}\item static const bool \textbf{ Has\+Duplicated\+Points} = false \begin{DoxyCompactList}\small\item\em This is true if a point can be included in more than one node. \end{DoxyCompactList}\item static const bool \textbf{ Has\+Overlapping\+Children} = true \begin{DoxyCompactList}\small\item\em This is true if the subspaces represented by the children of a node can overlap. \end{DoxyCompactList}\item static const bool \textbf{ Has\+Self\+Children} = false \begin{DoxyCompactList}\small\item\em This is true if the points contained in the first child of a node (Child(0)) are also contained in that node. \end{DoxyCompactList}\item static const bool \textbf{ Rearranges\+Dataset} = false \begin{DoxyCompactList}\small\item\em This is true if the tree rearranges points in the dataset when it is built. \end{DoxyCompactList}\item static const bool \textbf{ Unique\+Num\+Descendants} = true \begin{DoxyCompactList}\small\item\em This is true if the Num\+Descendants() method doesn\textquotesingle{}t include duplicated points. \end{DoxyCompactList}\end{DoxyCompactItemize} \subsection{Detailed Description} \subsubsection*{template$<$typename Tree\+Type$>$\newline class mlpack\+::tree\+::\+Tree\+Traits$<$ Tree\+Type $>$} The \doxyref{Tree\+Traits}{p.}{classmlpack_1_1tree_1_1TreeTraits} class provides compile-\/time information on the characteristics of a given tree type. These include traits such as whether or not a node knows the distance to its parent node, or whether or not the subspaces represented by children can overlap. These traits can be used for static compile-\/time optimization\+: \begin{DoxyCode} \textcolor{comment}{// This if statement will be optimized out at compile time!} \textcolor{keywordflow}{if} (TreeTraits::HasOverlappingChildren == \textcolor{keyword}{false}) \{ \textcolor{comment}{// Do a simpler computation because no children overlap.} \} \textcolor{keywordflow}{else} \{ \textcolor{comment}{// Do the full, complex calculation.} \} \end{DoxyCode} The traits can also be used in conjunction with S\+F\+I\+N\+AE to write specialized versions of functions\+: \begin{DoxyCode} \textcolor{keyword}{template}<\textcolor{keyword}{typename} TreeType> \textcolor{keywordtype}{void} Compute(TreeType& node, std::enable_if_t< TreeTraits::RearrangesDataset>*) \{ \textcolor{comment}{// Computation where special dataset-rearranging tree constructor is} \textcolor{comment}{// called.} \} \textcolor{keyword}{template}<\textcolor{keyword}{typename} TreeType> \textcolor{keywordtype}{void} Compute(TreeType& node, std::enable_if_t< !TreeTraits::RearrangesDataset>*) \{ \textcolor{comment}{// Computation where normal tree constructor is called.} \} \end{DoxyCode} In those two examples, the \doxyref{std\+::enable\+\_\+if\+\_\+t$<$$>$}{p.}{namespacestd_a93e9cb7fadbcfaa2afb5b94058b8e34c} class takes a boolean template parameter which allows that function to be called when the boolean is true. Each trait must be a static const value and not a function; only const values can be used as template parameters (or constexprs can be used too). By default (the unspecialized implementation of \doxyref{Tree\+Traits}{p.}{classmlpack_1_1tree_1_1TreeTraits}), each parameter is set to make as few assumptions about the tree as possible; so, even if \doxyref{Tree\+Traits}{p.}{classmlpack_1_1tree_1_1TreeTraits} is not specialized for a particular tree type, tree-\/based algorithms should still work. When you write your own tree, you must specialize the \doxyref{Tree\+Traits}{p.}{classmlpack_1_1tree_1_1TreeTraits} class to your tree type and set the corresponding values appropriately. See \doxyref{mlpack/core/tree/binary\+\_\+space\+\_\+tree/traits.\+hpp}{p.}{binary__space__tree_2traits_8hpp} for an example. Definition at line 77 of file tree\+\_\+traits.\+hpp. \subsection{Member Data Documentation} \mbox{\label{classmlpack_1_1tree_1_1TreeTraits_ae435fd522971cd7cfd3064636aad08f8}} \index{mlpack\+::tree\+::\+Tree\+Traits@{mlpack\+::tree\+::\+Tree\+Traits}!Binary\+Tree@{Binary\+Tree}} \index{Binary\+Tree@{Binary\+Tree}!mlpack\+::tree\+::\+Tree\+Traits@{mlpack\+::tree\+::\+Tree\+Traits}} \subsubsection{Binary\+Tree} {\footnotesize\ttfamily const bool Binary\+Tree = false\hspace{0.3cm}{\ttfamily [static]}} This is true if the tree always has only two children. Definition at line 110 of file tree\+\_\+traits.\+hpp. \mbox{\label{classmlpack_1_1tree_1_1TreeTraits_a74d33aa1842a86c50e913427bce29f04}} \index{mlpack\+::tree\+::\+Tree\+Traits@{mlpack\+::tree\+::\+Tree\+Traits}!First\+Point\+Is\+Centroid@{First\+Point\+Is\+Centroid}} \index{First\+Point\+Is\+Centroid@{First\+Point\+Is\+Centroid}!mlpack\+::tree\+::\+Tree\+Traits@{mlpack\+::tree\+::\+Tree\+Traits}} \subsubsection{First\+Point\+Is\+Centroid} {\footnotesize\ttfamily const bool First\+Point\+Is\+Centroid = false\hspace{0.3cm}{\ttfamily [static]}} This is true if the first point of each node is the centroid of its bound. Definition at line 94 of file tree\+\_\+traits.\+hpp. \mbox{\label{classmlpack_1_1tree_1_1TreeTraits_af080c27547c6b45c37173e0df36d63be}} \index{mlpack\+::tree\+::\+Tree\+Traits@{mlpack\+::tree\+::\+Tree\+Traits}!Has\+Duplicated\+Points@{Has\+Duplicated\+Points}} \index{Has\+Duplicated\+Points@{Has\+Duplicated\+Points}!mlpack\+::tree\+::\+Tree\+Traits@{mlpack\+::tree\+::\+Tree\+Traits}} \subsubsection{Has\+Duplicated\+Points} {\footnotesize\ttfamily const bool Has\+Duplicated\+Points = false\hspace{0.3cm}{\ttfamily [static]}} This is true if a point can be included in more than one node. Definition at line 89 of file tree\+\_\+traits.\+hpp. \mbox{\label{classmlpack_1_1tree_1_1TreeTraits_aace4b7477b18c336612f4f4d3046eb37}} \index{mlpack\+::tree\+::\+Tree\+Traits@{mlpack\+::tree\+::\+Tree\+Traits}!Has\+Overlapping\+Children@{Has\+Overlapping\+Children}} \index{Has\+Overlapping\+Children@{Has\+Overlapping\+Children}!mlpack\+::tree\+::\+Tree\+Traits@{mlpack\+::tree\+::\+Tree\+Traits}} \subsubsection{Has\+Overlapping\+Children} {\footnotesize\ttfamily const bool Has\+Overlapping\+Children = true\hspace{0.3cm}{\ttfamily [static]}} This is true if the subspaces represented by the children of a node can overlap. Definition at line 84 of file tree\+\_\+traits.\+hpp. \mbox{\label{classmlpack_1_1tree_1_1TreeTraits_ad3cb9cb573f3b0e51f99664fb8d29fef}} \index{mlpack\+::tree\+::\+Tree\+Traits@{mlpack\+::tree\+::\+Tree\+Traits}!Has\+Self\+Children@{Has\+Self\+Children}} \index{Has\+Self\+Children@{Has\+Self\+Children}!mlpack\+::tree\+::\+Tree\+Traits@{mlpack\+::tree\+::\+Tree\+Traits}} \subsubsection{Has\+Self\+Children} {\footnotesize\ttfamily const bool Has\+Self\+Children = false\hspace{0.3cm}{\ttfamily [static]}} This is true if the points contained in the first child of a node (Child(0)) are also contained in that node. Definition at line 100 of file tree\+\_\+traits.\+hpp. \mbox{\label{classmlpack_1_1tree_1_1TreeTraits_aba7aca795787a6fe3e8bbdae13edc70b}} \index{mlpack\+::tree\+::\+Tree\+Traits@{mlpack\+::tree\+::\+Tree\+Traits}!Rearranges\+Dataset@{Rearranges\+Dataset}} \index{Rearranges\+Dataset@{Rearranges\+Dataset}!mlpack\+::tree\+::\+Tree\+Traits@{mlpack\+::tree\+::\+Tree\+Traits}} \subsubsection{Rearranges\+Dataset} {\footnotesize\ttfamily const bool Rearranges\+Dataset = false\hspace{0.3cm}{\ttfamily [static]}} This is true if the tree rearranges points in the dataset when it is built. Definition at line 105 of file tree\+\_\+traits.\+hpp. \mbox{\label{classmlpack_1_1tree_1_1TreeTraits_a416bd78d7883fd5c3bc22b858f7d7064}} \index{mlpack\+::tree\+::\+Tree\+Traits@{mlpack\+::tree\+::\+Tree\+Traits}!Unique\+Num\+Descendants@{Unique\+Num\+Descendants}} \index{Unique\+Num\+Descendants@{Unique\+Num\+Descendants}!mlpack\+::tree\+::\+Tree\+Traits@{mlpack\+::tree\+::\+Tree\+Traits}} \subsubsection{Unique\+Num\+Descendants} {\footnotesize\ttfamily const bool Unique\+Num\+Descendants = true\hspace{0.3cm}{\ttfamily [static]}} This is true if the Num\+Descendants() method doesn\textquotesingle{}t include duplicated points. Definition at line 116 of file tree\+\_\+traits.\+hpp. The documentation for this class was generated from the following file\+:\begin{DoxyCompactItemize} \item /var/www/mlpack.\+ratml.\+org/mlpack.\+org/\+\_\+src/mlpack-\/git/src/mlpack/core/tree/\textbf{ tree\+\_\+traits.\+hpp}\end{DoxyCompactItemize}