dotplot.sty

\NeedsTeXFormat{LaTeX2e}
\RequirePackage{tikz}
\RequirePackage{ifthen}
\RequirePackage{blosum62}
\ProvidesPackage{dotplot}[2016/02/10 dotplot package]

\newcommand{\seqa}{A}
\newcommand{\seqb}{A}

\newcommand{\dotplot}[2]{%
    \renewcommand{\seqa}{#1}
    \renewcommand{\seqb}{#2}
    \begin{tikzpicture}[
    match/.style={rectangle, draw=black!100, fill=blue!35, minimum size=0.5cm},
    scale=0.5
    ]
    %\foreach \x [count=\xi] in {a, b, c, d, e, f, g, h} \node[draw] at (\xi, 1) {\x};

    \foreach \charA [count=\xi] in \seqa
    {%
        \node[] at (\xi+1, 1) {\charA};
        \foreach \charB [count=\yi] in \seqb
        {%
            \draw (0.5,-\yi+1.5) -- (\xi+1.5,-\yi+1.5);
            \draw (\xi+0.5, +1.5) -- (\xi+0.5,-\yi+0.5);
            \ifnum\xi=1
                \node[] at (1, -\yi+1) {\charB};
            \fi
            \ifthenelse{\equal{\charA}{\charB}}{%
                \node [match] at (\xi+1,-\yi+1) {};
            }{}
        }
    }
    \end{tikzpicture}
}

\newcommand{\protdotplot}[2]{%
    \renewcommand{\seqa}{#1}
    \renewcommand{\seqb}{#2}
    \begin{tikzpicture}[
    match/.style={rectangle, draw=black!100, fill=blue!35, minimum size=0.5cm},
    scale=0.5
    ]
    %\foreach \x [count=\xi] in {a, b, c, d, e, f, g, h} \node[draw] at (\xi, 1) {\x};

    \foreach \charA [count=\xi] in \seqa
    {%
        \node[] at (\xi+1, 1) {\charA};
        \foreach \charB [count=\yi] in \seqb
        {%
            %\draw (0.5,-\yi+1.5) -- (\xi+1.5,-\yi+1.5);
            %\draw (\xi+0.5, +1.5) -- (\xi+0.5,-\yi+0.5);
            \ifnum\xi=1
                \node[] at (1, -\yi+1) {\charB};
            \fi

            \node [match, fill=blue!\the\numexpr(\blosumLookup{\charA}{\charB}+4)*11\relax] at (\xi+1,-\yi+1) {};
        }
    }
    \end{tikzpicture}
}