Vertical alignment of pgfplots groupplots with uneven number of plots

Question

I'm trying to produce a 2 colums by 2/3 rows groupplot in pgfplots. On the first column I have 2 plots, on the second I have 3 plots. I want to distribute the plot heights for the side with fewer plots to have the same outer bounding box.

Using two different heights for the first and second column plots I can, at least somewhat, make them fit in total height. However, vertically the first row is aligned on the centers of the two first-row plots (a & b). What I want to achieve is, that the bounding box top of the first row is aligned vertically and the bounding box bottom line is aligned for the last plot.

I found anchor=north here, but it changes only the right plot's position (b), that is then aligned with the left vertical center (of plot a). Even if I add the option for both plots.

My code looks somewhat like:

\documentclass{standalone}
% pictures drawn with TikZ
\usepackage{tikz,pgfplots}
\usetikzlibrary{pgfplots.groupplots} % needs to be loaded exactly like this
\pgfplotsset{compat=newest}
\begin{document}
\newcommand{\heightLarge}{4.7cm}
\begin{tikzpicture}
  \begin{groupplot}
[
group style={group size=2 by 3, % cols by rows
    horizontal sep=50pt,
},
  width= 0.385\textwidth,
  height=3.2cm,
  xmin=0,
  xmax=14,
  xlabel={time in s},
]
\nextgroupplot[% #1
  ymin=0.0,
  ymax=2/2,
  ylabel={a},
  height=\heightLarge,
]
\addplot[]{sin(x)};
\nextgroupplot[% #2
  ymin=0,
  ymax=0.2/0.03,
  ylabel={b},
]
\addplot[]{sin(x)};
\nextgroupplot[% #3
  ymin=-0.8,
  ymax=0.8,
  height=\heightLarge,
]
\addplot[]{sin(x)};
\nextgroupplot[% #4
  ymin=2.5/3,
  ymax=4.2/3,
]
\addplot[]{sin(x)};
\nextgroupplot[group/empty plot] % #5
\nextgroupplot[% #6
  ymin=0,
  ymax=60,
]
\addplot[]{sin(x)};
\end{groupplot}
\end{tikzpicture}%
\end{document}

Answer 1

I do not think that groupplot can be used to make a layout like this. Luckily it is not too difficult to do manually.

\documentclass[tikz, border=1cm]{standalone}
\usetikzlibrary{calc}
\usepackage{pgfplots}
\pgfplotsset{compat=1.18}
\begin{document}
\begin{tikzpicture}
\pgfplotsset{
xmin=0, xmax=14, 
xlabel={time in s}, xlabel style={yshift=4pt},
}
\begin{axis}[
name=plot1,
width=5cm, height=5cm,
ymin=0, ymax=1,
]
\end{axis}
\begin{axis}[
name=plot2, at={($(plot1.south west)+(0,-1cm)$)}, anchor=north west,
width=5cm, height=5cm,
ymin=-1, ymax=1,
]
\end{axis}
\begin{axis}[
name=plot3, at={($(plot1.north east)+(1.5cm,0)$)}, anchor=north west,
width=5cm, height=3.5cm,
ymin=0, ymax=6,
]
\end{axis}
\begin{axis}[
name=plot4, at={($(plot1.north east)!0.5!(plot2.south east)+(1.5cm,0)$)}, anchor=west,
width=5cm, height=3.5cm,
ymin=0.5, ymax=1.4,
]
\end{axis}
\begin{axis}[
name=plot5, at={($(plot2.south east)+(1.5cm,0)$)}, anchor=south west,
width=5cm, height=3.5cm,
ymin=0, ymax=60,
]
\end{axis}
\end{tikzpicture}
\end{document}

Edit: A layout with seven graphs

\documentclass[tikz, border=1cm]{standalone}
\usetikzlibrary{calc}
\usepackage{pgfplots}
\pgfplotsset{compat=1.18}
\begin{document}
\begin{tikzpicture}
\pgfplotsset{xmin=0, xmax=1, ymin=0, ymax=1, width=5cm, height=3cm}
\begin{axis}[name=plot1] \end{axis}
\begin{axis}[name=plot2, at={($(plot1.south west)+(0,-2cm)$)}, anchor=north west] \end{axis}
\begin{axis}[name=plot3, at={($(plot2.south west)+(0,-2cm)$)}, anchor=north west] \end{axis}
\begin{axis}[name=plot4, at={($(plot1.north east)+(1cm,0)$)},  anchor=north west] \end{axis}
\begin{axis}[name=plot7, at={($(plot3.south east)+(1cm,0)$)},  anchor=south west] \end{axis}
\begin{axis}[name=plot5, at={($(plot4)!1/3!(plot7)$)},  anchor=center] \end{axis}
\begin{axis}[name=plot6, at={($(plot4)!2/3!(plot7)$)},  anchor=center] \end{axis}
\end{tikzpicture}
\end{document}