LaTeX barplot: one x-axis, two y-axis

Question

I want to plot a bar plot with LaTeX with the layout that you can see in the picture that I've done with PowerPoint:

I don't want to do a subplot kind of graph since the datasets include the same data but collected in two different moments of an experiment.

Any idea on how to do it?

Answer 1

This is quite an easy task for PGFPlots. Because you weren't very specific for your needs, here I also just present an example on how to do it, using some dummy data copied from the manual.

If you have experimental data in a file and you need to use "symbolic coordinates", please also have a look at Remove the space between bars and axis. And if you really should need a second y-axis, also this can be done. For that have a look at Second y-axis inside groupplot.

Hopefully this gives you at least a good start. If you later need some more assistance in details, please feel free to ask a Follow-up question then.

\documentclass[border=5pt]{standalone}
\usepackage{pgfplots}
    \usetikzlibrary{pgfplots.groupplots}
    \pgfplotsset{compat=1.14}
\begin{document}
    \begin{tikzpicture}
        \begin{groupplot}[
            group style={
                group size=1 by 2,
                x descriptions at=edge bottom,
                y descriptions at=edge left,
                vertical sep=5mm,
            },
            ybar,
            enlargelimits=0.15,
            ylabel={\#participants},
            xtick=data,
            symbolic x coords={tool8,tool9,tool10},
            nodes near coords,
        ]
        \nextgroupplot
            \addplot coordinates {(tool8,7) (tool9,9) (tool10,4)};
            \addplot coordinates {(tool8,4) (tool9,4) (tool10,4)};
            \addplot coordinates {(tool8,1) (tool9,1) (tool10,1)};
        \nextgroupplot
            \addplot coordinates {(tool8,7) (tool9,9) (tool10,4)};
            \addplot coordinates {(tool8,4) (tool9,4) (tool10,4)};
            \addplot coordinates {(tool8,1) (tool9,1) (tool10,1)};
        \end{groupplot}
    \end{tikzpicture}
\end{document}