standalone_scatter_with_marginal_histograms.tex

\documentclass[border=1mm]{standalone}

\usepackage{pgfplots}
\pgfplotsset{compat=1.18} % set pgf compatibility to 1.18

\begin{document}

\begin{tikzpicture}[
    /pgfplots/scale only axis,
    /pgfplots/width=3cm,
    /pgfplots/height=3cm
]

% The scatterplot
\begin{axis}[
    name=main axis, % Name the axis, so we can position the histograms relative to this axis
    xlabel = $x$, ylabel = $y$,
    title = {Scatterplot and Marginal\\Histograms of Original Data},
 title style={at={(.725,1.8)},anchor=north,align=center},
]
\addplot [only marks, mark size=1.25, opacity=.5] table {data.csv};
\end{axis}

% The histogram for the x axis
\begin{axis}[
    anchor=south west,
    at=(main axis.north west),
    height=1.5cm,
    xtick=\empty,
]
\addplot [
    hist={data=x}, % By default, the y values would be used for calculating the histogram
    fill=gray!50,
] table {data.csv};
\end{axis}


% The histogram for the y axis
\begin{axis}[
    anchor=north west,
    at=(main axis.north east),
    width=1.5cm,
    ytick=\empty
]
\addplot [
    % For swapping the x and y axis, we have to change a couple of options...
    hist={handler/.style={xbar interval}}, % ... use bars instead of columns ...
    x filter/.code=\pgfmathparse{rawy}, % ... interpret the x values of the histogram as y values 
    y filter/.code=\pgfmathparse{rawx}, % ... and vice versa.
    fill=gray!50,
    ] table {data.csv};
\end{axis}
\end{tikzpicture}


\end{document}