Which algorithm packages can I use for indentation based (python like) display?

Question

I see a few papers such as this and this that uses an indentation based display. Note that they do not have an endif or an endwhile. What algorithm package is being used here? Or how do I get a similar effect?

Answer 1

The following is a starting point, using algorithm2e:

\documentclass{article}

\usepackage{xcolor,amsmath}
\usepackage[linesnumbered,ruled,vlined]{algorithm2e}
\DontPrintSemicolon

% Define pseudocode formatting
\renewcommand{\KwSty}[1]{\textnormal{\textcolor{blue!90!black}{\ttfamily\bfseries #1}}\unskip}
\renewcommand{\ArgSty}[1]{\textnormal{\ttfamily #1}\unskip}
\SetKwComment{Comment}{\color{green!50!black}// }{}
\renewcommand{\CommentSty}[1]{\textnormal{\ttfamily\color{green!50!black}#1}\unskip}
\newcommand{\assign}{\leftarrow}
\newcommand{\var}{\texttt}
\newcommand{\FuncCall}[2]{\texttt{\bfseries #1(#2)}}
\SetKwProg{Function}{function}{}{}
\renewcommand{\ProgSty}[1]{\texttt{\bfseries #1}}

\begin{document}

\begin{algorithm}
  \caption{Dynamic PCA}
  \Comment{$\theta_{\mathrm{exp}}$ is globally given, and initially set to $\infty$.}
  \Function{ExpandBasisIfInteresting($B$, $\Sigma$, $\vec{x}$)}{
    \If{$\var{loss} > \theta_{\mathrm{exp}}$}{
      $\var{loss} \assign \sqrt{\lVert \vec{x} \rVert^2 - \lVert \vec{x}^T B \rVert^2}$
        \Comment{By Pythagoras}
      $B, \Sigma \assign \FuncCall{Append}{$B$, $\Sigma$, $\vec{x}$}$\;
      $B \assign \FuncCall{GramSchmidt}{$B$}$\;
    }
    $\theta_{\mathrm{exp}} \assign \FuncCall{UpdateLoss}{$\theta_{\mathrm{exp}}$, \var{loss}}$\;
    \Return{$B$, $\Sigma$}\;
  }
  \Function{PeriodicDecompose($B$, $\Sigma$)}{
    \If{\FuncCall{IsOneMinutePassed}{}}{
      $B, \Sigma \assign \FuncCall{PCA}{$B$, $\Sigma$}$\;
    }
    \Return{$B$, $\Sigma$}\;
  }
  \Comment{The main function}
  \Function{DynPCA($B$, $\Sigma$, $\vec{x}$, $s$)}{
    $B, \Sigma \assign \FuncCall{ExpandBasisIfInteresting}{$B$, $\Sigma$, $\vec{x}$}$\;
    $\Sigma \assign \FuncCall{UpdateCovMatrix}{$B$, $\Sigma$, $\vec{x}$, $s$}$\;
    $B', \Sigma' \assign \FuncCall{PeriodicDecompose}{$B$, $\Sigma$}$\;
    \Return{$B'$, $\Sigma'$}
  }
\end{algorithm}

\end{document}

Answer 2

The algorithm2e package offers the above (not by default, but it is quite customizable).