[Tex/LaTex] understanding how to have one legend for a group plot

pgfplotstikz-pgf

I know this question has been asked in various forms before, but I just do not understand the syntax of one of the solutions that I would like to use. I have checked the documentation of Tikz and pfg plot to no avail, and I am hoping someone can clarify how this example works.

What I would like to do is have a 2row/1col group plot with the legend either to the right or underneath (but would like to try both to see what looks better if possible). Here is an example online from PGFPlots – trying to combine legends that does work.

My question comes down to not understanding some of the syntax here. The original question explained some of the syntax for the second \path command, but I am still confused. What do the arguments to the \path commands (first and second mean), why do anchor-south in the matrix command and what is the significance of the at[…]. If someone could clearly explain these things, that would be really great. I couldn't find resources online that made things clear to me.

\documentclass[margin=5mm]{standalone}
\usepackage{pgfplots}
\usetikzlibrary{matrix}
\usepgfplotslibrary{groupplots}
\pgfplotsset{compat=newest}
\begin{document}

\begin{tikzpicture}
    \begin{groupplot}[group style={group size= 2 by 4},height=5cm,width=6.4cm]
        \nextgroupplot[title=type1,ylabel={Range1 }]
                \addplot[blue] {x};\label{plots:plot1}
                \addplot[red] {x^2};\label{plots:plot2}
                \addplot[green] {2*x};\label{plots:plot3}
                \coordinate (top) at (rel axis cs:0,1);% coordinate at top of the first plot
        \nextgroupplot[title=type2]
                \addplot[blue]{x};
        \nextgroupplot[ylabel={Range2 }]
                \addplot[blue]{x};
        \nextgroupplot
                \addplot[blue]{x};
        \nextgroupplot[ylabel={Range3 }]
                \addplot[blue]{x};
        \nextgroupplot
                \addplot[blue]{x};
        \nextgroupplot[xlabel={Number of Threads},ylabel={Range4 }]
                \addplot[blue]{x};
        \nextgroupplot[xlabel={Number of Threads}]
                \addplot[blue]{x};
                \coordinate (bot) at (rel axis cs:1,0);% coordinate at bottom of the last plot
    \end{groupplot}
    \path (top-|current bounding box.west)-- 
          node[anchor=south,rotate=90] {throughput} 
          (bot-|current bounding box.west);
% legend
\path (top|-current bounding box.north)--
      coordinate(legendpos)
      (bot|-current bounding box.north);
\matrix[
    matrix of nodes,
    anchor=south,
    draw,
    inner sep=0.2em,
    draw
  ]at([yshift=1ex]legendpos)
  {
    \ref{plots:plot1}& curve 1&[5pt]
    \ref{plots:plot2}& curve2&[5pt]
    \ref{plots:plot3}& curve 3\\};
\end{tikzpicture}
\end{document}

Best Answer

This shows how to put a 1 column legend on the right. It occurred to me that your legend comes from one plot instead of combining entries from multiple plots, which simplifies matters.

\documentclass[margin=5mm]{standalone}
\usepackage{pgfplots}
\usetikzlibrary{matrix}
\usepgfplotslibrary{groupplots}
\pgfplotsset{compat=newest}
\begin{document}

\begin{tikzpicture}
    \begin{groupplot}[group style={group size= 2 by 4},height=5cm,width=6.4cm]
        \nextgroupplot[title=type1,ylabel={Range1 },legend to name=zelda]
                \addplot[blue] {x};\addlegendentry{curve 1};
                \addplot[red] {x^2};\addlegendentry{curve 2};
                \addplot[green] {2*x};\addlegendentry{curve 3};
                \coordinate (top) at (rel axis cs:0,1);% coordinate at top of the first plot
        \nextgroupplot[title=type2]
                \addplot[blue]{x};
        \nextgroupplot[ylabel={Range2 }]
                \addplot[blue]{x};
        \nextgroupplot
                \addplot[blue]{x};
        \nextgroupplot[ylabel={Range3 }]
                \addplot[blue]{x};
        \nextgroupplot
                \addplot[blue]{x};
        \nextgroupplot[xlabel={Number of Threads},ylabel={Range4 }]
                \addplot[blue]{x};
        \nextgroupplot[xlabel={Number of Threads}]
                \addplot[blue]{x};
                \coordinate (bot) at (rel axis cs:1,0);% coordinate at bottom of the last plot
    \end{groupplot}
    \path (top)--(bot) coordinate[midway] (group center);
    \node[above,rotate=90] at (group center -| current bounding box.west) {throughput};
    \node[right=1em,inner sep=0pt] at(group center -| current bounding box.east) {\pgfplotslegendfromname{zelda}};
\end{tikzpicture}
\end{document}

Related Solutions

[Tex/LaTex] Custom legend for intensity plot

You can activate the colormap simply by calling colormap in the axis options. The default range is 0 to 1, so you wouldn't even need to do adjust it in this case, but usually you would use point meta min=<lower>, point meta max=<upper>.

There are a number of predefined colormaps which are documented in the manual. There is a grayscale colormap which assigns black to the lowest and white to the highest values. In case you want a different mapping, you can create your own using a statement like

colormap={whiteblack}{gray(0cm)=(1); gray(1cm)=(0)}

You can customise the colorbar using the same options that apply to axis environments by passing the options to colorbar style.

\documentclass[border=5mm]{standalone}
\usepackage{pgfplots}

\begin{document}
\begin{tikzpicture}
\begin{axis}[
    axis equal image,
    enlargelimits=false,
    axis on top,
    colorbar,
    point meta min=0, point meta max=1,
    colormap={whiteblack}{gray(0cm)=(1); gray(1cm)=(0)},
    colorbar style={
        title=Intensity,
        at={(1.1,0)}, % Coordinate system relative to the main axis. (1,1) is upper right corner of main axis.
        anchor=south west,
        height=2/3*\pgfkeysvalueof{/pgfplots/parent axis height}, % Scale the colorbar relative to the main axis
        /pgf/number format/.cd, % Change the key directory to /pgf/number format
        fixed, fixed zerofill, precision=1,
        /tikz/.cd  % Change back to the normal key directory
    }
]
\addplot graphics [xmin=-1, xmax=1, ymin=-1, ymax=1] {image};
\end{axis}
\end{tikzpicture}
\end{document}

[Tex/LaTex] pgfplots: percentage in matrix plot

It does not work in your MWE because you are overwriting it by also giving the option nodes near coors to the \addplot command. Remove the latter one (or specify format here), and it will print. I added a thinspace before the percentage sign, although it can also be recommended to load the siunitx package and let that format and typeset the values for you.

Anyway, here's the quickfixed version:

\documentclass[border=3pt]{standalone}
\usepackage{pgfplots}
\pgfplotsset{%
  width=5cm,
  height=18cm,
  compat=1.13,
  colormap={blackwhite}{gray(0cm)=(1); gray(1cm)=(0.5)},
  xticklabels={LPIBG, ALL, HPIBG},
  xtick={0,...,2},
  ytick=\empty
}

\begin{document}
\begin{tikzpicture}
\begin{axis}[%
  enlargelimits=false,
  xlabel style={font=\footnotesize},
  ylabel style={font=\footnotesize},
  legend style={font=\footnotesize},
  xticklabel style={font=\footnotesize},
  yticklabel style={font=\footnotesize},
  colorbar,
  colorbar style={%
    ytick={0,20,40,60,80,100},
    yticklabels={0,20,40,60,80,100},
    yticklabel={\pgfmathprintnumber\tick\,\%},
    yticklabel style={font=\footnotesize}
  },
  point meta min=0,
  point meta max=100,
  nodes near coords={\pgfmathprintnumber\pgfplotspointmeta\,\%},
  every node near coord/.append style={xshift=0pt,yshift=-7pt, black, font=\footnotesize},
]

\addplot[
matrix plot,
mesh/cols=3,
point meta=explicit]
table[meta=C]{
  x y C
  0 0 80
  1 0 36
  2 0 40
  0 1 64
  1 1 80
  2 1 60
  0 2 52
  1 2 84
  2 2 72
  0 3 72
  1 3 28
  2 3 32
  0 4 56
  1 4 84
  2 4 80
  0 5 72
  1 5 52
  2 5 44
  0 6 4
  1 6 84
  2 6 41
  0 7 37
  1 7 69
  2 7 84
  0 8 63
  1 8 53
  2 8 82
  0 9 78
  1 9 74
  2 9 39
  0 10 39
  1 10 63
  2 10 88
  0 11 76
  1 11 74
  2 11 49
  0 12 39
  1 12 6
  2 12 88
  0 13 46
  1 13 33
  2 13 75
  0 14 88
  1 14 67
  2 14 54
  0 15 79
  1 15 83
  2 15 75
  0 16 50
  1 16 46
  2 16 71
  0 17 92
  1 17 71
  2 17 75
  0 18 46
  1 18 33
  2 18 8
};
\end{axis}
\end{tikzpicture}
\end{document}

Best Answer

Related Solutions

[Tex/LaTex] Custom legend for intensity plot

[Tex/LaTex] pgfplots: percentage in matrix plot

Related Question