How to create assignment border matrix like this [duplicate]

Question

I want to create assignment matrix like this

\usepackage{kbordermatrix,blkarray}
\usepackage{amsmath}
\usepackage{amsmath,stackengine}
\stackMath
\[
\stackinset{c}{-2.8\baselineskip}{c}{}{\rule{.4pt}{5.2\baselineskip}}{%
\stackinset{c}{1.9\baselineskip}{c}{}{\rule{.4pt}{5.2\baselineskip}}{%
\stackinset{c}{3.1\baselineskip}{c}{}{\rule{.4pt}{5.2\baselineskip}}{%
\stackinset{c}{}{c}{2\baselineskip}{\rule{6.9\baselineskip}{.4pt}}{%
\stackinset{c}{}{c}{-3\baselineskip}{\rule{6.9\baselineskip}{.4pt}}{%
\bbordermatrix{ & 1 & 2 & 3 & 4 & 5 & 6 \cr
              1 & 1.5 & 3.5 & 1 & (1) & 1 & 4 \cr
              2 & 1.8 & (1) & 3.1 & 2.6 & 1.9 & 1.8 \cr
              3 & (1) & 1 & 1 & 1.4 & 1.1 & 2.1 \cr
              4 & 3.8 & 4 & (1) & 5.6 & 2.8 & 2.2 \cr
              5 & 3 & 3.3 & 1 & 4.6 & 4.6 & 5  \cr
              6 & 4.8 & 4.9 & 3.2 & 5.5 & 2.8 & (1) \cr
              }}}}}}
\]

Answer 1

Here is a way to obtain it with blkarray and pstricks. I added auto-pst-pdf to compile with pdflatex, but this requires to launch the compiler with the enable-write18 switch (MiKTeX) or -shell-escape (TeX Live, MacTeX):

\documentclass[12pt, svgnames]{article}
\usepackage[utf8]{inputenc}
\usepackage{blkarray, bigstrut, amsmath}
\usepackage{pst-node, auto-pst-pdf}
\begin{document}

\[ \begin{postscript}
    \begin{blockarray}{c*{6}{c}}
      \begin{block}{c*{6}{>{$ \footnotesize $}c}}
        & \thead{1} & \thead{2} & \thead{3} & \thead{4} & \thead{5} & \thead{6} \\
      \end{block}
      \begin{block}{>{\footnotesize }c(*{6}{c})}
        1 & \rnode{A}{1.5} & 3.5 & 1 & (1) & \Rnode{E}{1} & \rnode{B}{4}\bigstrut[t] \\
        2 & 1.8 & (1) & 3.1 & 2.6 & 1.9 & 1.8 \\
        3 & (1) & 1 & 1 & 1.4 & 1.1 & 2.1 \\
        4 & 3.8 & 4 & (1) & 5.6 & 2.8 & 2.2 \\
        5 & 3 & 3.3 & 1 & 4.6 & 4.6 & 5 \\
        6 & \Rnode{D}{4.8} & 4.9 & 3.2 & 5.5 & \Rnode{F}{2.8} & \Rnode{C}{(1)}\bigstrut[b] \\
      \end{block}
    \end{blockarray}
    \psset{linewidth=0.4pt, linecolor=LightSteelBlue, nodesep = -1.4em}
    \ncline[nodesepB=-.8em]{A}{B}
    \ncline{C}{D}
    \psset{nodesep=-1em}
    \ncline{A}{D}
    \ncline{B}{C}
    \ncline{E}{F}
  \end{postscript} \]

\end{document}