pgfplots: How to align plot width to same width as legend?

Question

The user marmot has posted a nice approach to put a legend below a multigraph diagram.

Minimum Working Example (MWE):

\documentclass[border=5mm]{standalone}
\usepackage{pgfplots}
\usetikzlibrary{positioning}
\pgfplotsset{compat=newest, scale only axis}
\begin{document}
\pgfplotsset{superb legend/.style={legend style                                = {draw=none,
                 legend columns                          = 3,
                 /tikz/every even column/.append style   = {column sep=0.5cm,
                 text width=7em},
                 /tikz/every odd column/.append style    = {column sep=0.15cm,
                  text width=7em},
                 }}}
\begin{tikzpicture}
\begin{scope}[local bounding box=plots]
 \begin{axis}[
             axis y line*                                = left,
             legend to name                              = legA,
             superb legend
             ]%
             \addplot coordinates {(0,0) (1,1)};
             \addplot coordinates {(1,0) (0,1)};
             \addplot coordinates {(0,1) (1,1)};
             \legend{Graph 1, Graph 2, Graph 3};
 \end{axis}%
 %
 \begin{axis}[
             axis x line                                 = none,
             axis y line*                                = right,
             legend to name                              = legB,
             superb legend
             ]%
             \addplot coordinates {(0,1) (1,0)};
             \addplot coordinates {(0,0.5) (1,0.5)};
             \addplot coordinates {(0,0.15) (1,0.15)};
             \legend{Graphinggraph~4, Graphinggraph~5, Graphinggraph~6};
 \end{axis}%
 %
 \begin{axis}[
             axis x line                                 = none,
             axis y line*                                = right,
             legend to name                              = legC,
             superb legend
             ]%
             \pgfplotsset%
                 {%
                 every outer y axis line/.style          = {xshift=2cm},
                 every tick/.style                       = {xshift=2cm},
                 every y tick label/.style               = {xshift=2cm},
                 }%
             \addplot coordinates {(0.5,0) (0.5,1)};
             \addplot coordinates {(0.6,0) (0.6,1)};
             \addplot coordinates {(0.7,0) (0.7,1)};
             \legend{Graphgraph 7, Graphgraph 8, Graphgraph 9};
 \end{axis}%
\end{scope}
\node[below=3.5em of plots.south] (legA) {\ref{legA}};
\node[below=-0.5em of legA] (legB) {\ref{legB}};
\node[below=-0.5em of legB] (legC) {\ref{legC}};
\draw (legA.north west) rectangle (legC.south east);
\end{tikzpicture}
\end{document}

Screenshot of the result:

Description of the issue:

Would it be possible to adjust the width of the plot to the width of the legend box (see upper screenshot with red markings)?

Or, the other way around:

Adjust the width of the legend box to the width of the plot?

How can I solve that nicely without playing around with the legend items text width? Maybe we can create some global variable to specify the widths of legend and plot together?

score 4 · Accepted Answer · 2019-03-22T14:53:19.517

This is sort of a "chicken or egg problem" because we can only build up the legend when the plots are done, but the plots should adjust their size to the one of the legend. The way this can be solved in LaTeX is to write the width to the aux file, from where it will be read in the next compilation and can be used. This is also used in the fantastic tikzmark library and more generally when coordinates are saved and used with remember picture. Yes, this means you need to compile more than once (at least three times here because in the first run the legends are only question marks), but if you are willing to do that, this seems to work.

\documentclass[border=5mm]{standalone}
\usepackage{pgfplots}
\usetikzlibrary{positioning,calc}
\pgfplotsset{compat=newest, scale only axis}
\begin{document}
\pgfplotsset{superb legend/.style={legend style                                = {draw=none,
                 legend columns                          = 3,
                 /tikz/every even column/.append style   = {column sep=0.5cm,
                 text width=7em},
                 /tikz/every odd column/.append style    = {column sep=0.15cm,
                  text width=7em},
                 }}}
\begin{tikzpicture}
\ifdefined\mylegendwidth
\ifdim\mylegendwidth<0pt
\pgfmathsetmacro{\mywidth}{abs(\mylegendwidth)}
\def\mylegendwidth{\mywidth pt}
\fi
\else
\typeout{Please\space recompile\space your\space file!}
\def\mylegendwidth{10cm}
\fi
\pgfplotsset{width=\mylegendwidth}
\begin{scope}[local bounding box=plots]
 \begin{axis}[
             axis y line*                                = left,
             legend to name                              = legA,
             superb legend
             ]%
             \addplot coordinates {(0,0) (1,1)};
             \addplot coordinates {(1,0) (0,1)};
             \addplot coordinates {(0,1) (1,1)};
             \legend{Graph 1, Graph 2, Graph 3};
 \end{axis}%
 %
 \begin{axis}[
             axis x line                                 = none,
             axis y line*                                = right,
             legend to name                              = legB,
             superb legend
             ]%
             \addplot coordinates {(0,1) (1,0)};
             \addplot coordinates {(0,0.5) (1,0.5)};
             \addplot coordinates {(0,0.15) (1,0.15)};
             \legend{Graphinggraph~4, Graphinggraph~5, Graphinggraph~6};
 \end{axis}%
 %
 \begin{axis}[
             axis x line                                 = none,
             axis y line*                                = right,
             legend to name                              = legC,
             superb legend
             ]%
             \pgfplotsset%
                 {%
                 every outer y axis line/.style          = {xshift=2cm},
                 every tick/.style                       = {xshift=2cm},
                 every y tick label/.style               = {xshift=2cm},
                 }%
             \addplot coordinates {(0.5,0) (0.5,1)};
             \addplot coordinates {(0.6,0) (0.6,1)};
             \addplot coordinates {(0.7,0) (0.7,1)};
             \legend{Graphgraph 7, Graphgraph 8, Graphgraph 9};
 \path (current axis.west) coordinate (aux1)  ([xshift=2cm]current axis.east)
  coordinate (aux2);
 \end{axis}%
\end{scope}
\node[anchor=north west] at ([yshift=-3.5em]plots.south-|aux1) (legA) {\ref{legA}};
\node[below=-0.5em of legA] (legB) {\ref{legB}};
\node[below=-0.5em of legB] (legC) {\ref{legC}};
\draw let \p1=($(legC.east)-(legA.west)$),\p2=($(aux2)-(aux1)$) in
[/utils/exec=\pgfmathsetmacro{\mywidth}{\mylegendwidth+\x1-\x2}%
\xdef\mylegendwidth{\mywidth pt}]
 (legA.north west) rectangle (legC.south east);
\makeatletter
 \immediate\write\@mainaux{\xdef\string\mylegendwidth{\mylegendwidth}\relax}
\makeatother
\end{tikzpicture}
\end{document}

Does this approach work fine as well when using Joseph Wright's approach to externalize compiling of memory-intensive plots? https://tex.stackexchange.com/a/7965/78784 I fear that we could run into some issue because the .aux-file won't be generated like before, no? — Dave, Apr 13 '19 at 12:54
Unfortunately yes, I used Joseph Wrights approach from the upper URL, but the legend won't fit anymore then. — Dave, Apr 13 '19 at 13:41
I have posted a new question concerning this. Maybe you have an idea about how to solve? https://tex.stackexchange.com/questions/484651/pgfplots-how-to-align-plot-width-to-same-width-as-legend-when-compiling-externa Thanks a lot in advance!! — Dave, Apr 13 '19 at 14:04
@Dave My problem is that I never use externalize. I am happy to believe what you are saying but at the moment I do not even get the thing use externalize with your original code, simply because I never use it and get unexpected errors. (And I already upvoted your question.) — , Apr 13 '19 at 14:10

score 2 · Answer 2 · answered Mar 22 '19 at 16:03

One can just scale the axis to match the legend size. Something like this:

\pgfplotsset{scale=1.12}

Not an elegant solution, but it works. ;)

Code:

\documentclass[border=5mm]{standalone}
\usepackage{pgfplots}
\usetikzlibrary{positioning}
\pgfplotsset{compat=newest, scale only axis,scale=1.12}
\pgfplotsset{scale=1.12}

\begin{document}
\pgfplotsset{superb legend/.style={     legend style                                = {draw=none,
                 legend columns                          = 3,
                 /tikz/every even column/.append style   = {column sep=0.5cm,
                 text width=7em},
                 /tikz/every odd column/.append style    = {column sep=0.15cm,
                  text width=7em},
                 }}}
\begin{tikzpicture}
\begin{scope}[local bounding box=plots]
 \begin{axis}[
             axis y line*                                = left,
             legend to name                              = legA,
             superb legend
             ]%
             \addplot coordinates {(0,0) (1,1)};
             \addplot coordinates {(1,0) (0,1)};
             \addplot coordinates {(0,1) (1,1)};
             \legend{Graph 1, Graph 2, Graph 3};
 \end{axis}%
 %
 \begin{axis}[
             axis x line                                 = none,
             axis y line*                                = right,
             legend to name                              = legB,
             superb legend
             ]%
             \addplot coordinates {(0,1) (1,0)};
             \addplot coordinates {(0,0.5) (1,0.5)};
             \addplot coordinates {(0,0.15) (1,0.15)};
             \legend{Graphinggraph~4, Graphinggraph~5, Graphinggraph~6};
 \end{axis}%
 %
 \begin{axis}[
             axis x line                                 = none,
             axis y line*                                = right,
             legend to name                              = legC,
             superb legend
             ]%
             \pgfplotsset%
                 {%
                 every outer y axis line/.style          = {xshift=2cm},
                 every tick/.style                       = {xshift=2cm},
                 every y tick label/.style               = {xshift=2cm},
                 }%
             \addplot coordinates {(0.5,0) (0.5,1)};
             \addplot coordinates {(0.6,0) (0.6,1)};
             \addplot coordinates {(0.7,0) (0.7,1)};
             \legend{Graphgraph 7, Graphgraph 8, Graphgraph 9};
 \end{axis}%
\end{scope}
\node[below=3.5em of plots.south] (legA) {\ref{legA}};
\node[below=-0.5em of legA] (legB) {\ref{legB}};
\node[below=-0.5em of legB] (legC) {\ref{legC}};
\draw (legA.north west) rectangle (legC.south east);
\end{tikzpicture}
\end{document}

Hahaha, this is the late-at-night-I want-to-get-finished-solution. :-) It works indeed, but is a little workaround. Thanks a lot, you get a point for that! :-) — Dave, Mar 22 '19 at 20:58

pgfplots: How to align plot width to same width as legend?

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