Using algorithm2e in figure environment

Question

I am using algorithm2e to explain my algorithm and surrounding it within float environment for IEEETran class as suggested in How to use the algorithm2e package with IEEEtran class?

Below is a sample code:

\documentclass[conference]{IEEEtran}
\usepackage[font=scriptsize]{caption}
\usepackage{subcaption}
\usepackage[plain, vlined, linesnumbered, noresetcount]{algorithm2e}
\makeatletter
\newcommand{\removelatexerror}{\let\@latex@error\@gobble}
\makeatother

\begin{document}
    \begin{figure}
        \removelatexerror
        \begin{algorithm}[H]
            \textbf{struct} Node \{ \\
            \Indp
            \textbf{Int} key;\\
            Node* child[2];\\
            \Indm
            \}; \\      
        \end{algorithm}
        \hrule
        \captionsetup{justification=centering}
        \caption{Node structure}
        \label{alg:NodeStructure}
    \end{figure}

    Figure \ref{alg:NodeStructure} represents a node in our tree
\end{document}

After I compile this code, I see a significant gap between the text and my algorithm. Is there any way to reduce this gap.

Answer 1

This is not particular to algorithm2e, but more so to do with the natural gaps between floats and the surrounding text as laid out by the class. Here is a quick view on the lengths involved in the separation:

The default lengths for IEEEtran are

• \floatsep: 0.85\baselineskip plus 0.2\baselineskip minus 0.2\baselineskip

• \textfloatsep: 1.55\baselineskip plus 0.2\baselineskip minus 0.4\baselineskip

• \intextsep: 0.85\baselineskip plus 0.2\baselineskip minus 0.2\baselineskip

These are all fairly large, but allow for some manoeuvring within a two-column layout (due to the plus and minus). Here's the view with \textfloatsep set to 0pt:

\documentclass[conference]{IEEEtran}

\usepackage[plain, vlined, linesnumbered, noresetcount]{algorithm2e}

\makeatletter
\newcommand{\removelatexerror}{\let\@latex@error\@gobble}
\makeatother

\begin{document}

\begin{figure}
  \removelatexerror
  \begin{algorithm}[H]
    \textbf{struct} Node \{ \\
    \Indp
    \textbf{Int} key;\\
    Node* child[2];\\
    \Indm
    \};
  \end{algorithm}
  \hrule
  \caption{Node structure}
\end{figure}

Lorem ipsum dolor sit amet, consectetur adipiscing elit. In finibus est in pulvinar semper. 
Nullam a mauris nibh. Aliquam egestas quam at vulputate condimentum. Suspendisse quis velit eros.

\newpage

\setlength{\textfloatsep}{0pt}

\begin{figure}
  \removelatexerror
  \begin{algorithm}[H]
    \textbf{struct} Node \{ \\
    \Indp
    \textbf{Int} key;\\
    Node* child[2];\\
    \Indm
    \};
  \end{algorithm}
  \hrule
  \caption{Node structure}
\end{figure}

Lorem ipsum dolor sit amet, consectetur adipiscing elit. In finibus est in pulvinar semper. 
Nullam a mauris nibh. Aliquam egestas quam at vulputate condimentum. Suspendisse quis velit eros.

\end{document}