[Tex/LaTex] How to multiple pgfplotstable columns be used in a legend

pgfplotspgfplotstable

I'd like to plot a few sets of data using the groupplots library of pgfplots. On each plot, I'd like to add a few other pieces of data that do not change from plot to plot. So I put the plot commands in a \foreach loop, but I can't get the legend entries to come from the input table describing these extra data. I tried something similar to the top answer in Use first row of a table as legend entry in pgfplot graph?, but it would not compile (when resolving references the second time around it did not like \colname).

Below is an example and the output. The correct answer will rename the labels from 'Model' to the columns from \modeltable. (It would also be nice to space the labels a bit further out in the horizontal direction…)

\documentclass[crop]{standalone}

\usepackage[svgnames]{xcolor}
\usepackage{pgfplots}
\usepackage{pgfplotstable}
\usepgfplotslibrary{groupplots}

\pgfplotsset{% global config
  compat=newest,
  every minor tick={very thin, gray},
  minor tick num=4,
  enlargelimits=0.02,
  group style={
    columns=2,
    xlabels at=edge bottom,
    ylabels at=edge left},
  every axis legend/.append style={
    legend cell align=left,
    legend columns=4
  }
}

\pgfplotstableread{
  Time      {Model A}   {Model G}   {Model Z}
  0         1           1           1
  1         1           2           2
  2         2           3           3
  3         3           4           4
  4         5           5           8
  5         8           6           10
  6         13          7           16
}\modeltable

\pgfplotstableread{
  Time      {Data 1}  {Data 2}
  0         1.3       2.3
  1         2.6       3.6
  2         3.8       4.8
  3         7.9       5.9
  4         6.3       7.3
  5         7.5       6.5
  6         9.0       8.9
}\datatable

\begin{document}

  \begin{tikzpicture}

    \begin{groupplot}[
      xlabel={Time},
      ylabel={Amplitude},
      every axis title shift=0,
      legend to name=grouplegend]

      \pgfplotsinvokeforeach{1,2}{%
        \nextgroupplot[title=Data $#1$]

        % Models
        \foreach \y in {1, 2, 3} {
          \addplot [smooth, dashed, color=DarkRed]
            table[x index=0, y index=\y] {\modeltable};
          %\pgfplotstablegetcolumnnamebyindex{\y}\of{\modeltable}\to{\colname}
          %\addlegendentry {\colname}
          \addlegendentry{Model}
        }

        % Data
        \addplot [only marks, mark=o]
          table[x index=0, y index=#1] {\datatable};
        \addlegendentry {Data}
      }

    \end{groupplot}

    \node (dummytitle) at ($(group c1r1.north)!0.5!(group c2r1.north)$)
      [above]{};
    \node (title) at (dummytitle.north)
      [above, yshift=\pgfkeysvalueof{/pgfplots/every axis title shift}]
      {Experimental Data};

    \node (legend) at ($(group c1r1.south)!0.5!(group c2r1.south)$)
      [below, yshift=-2\pgfkeysvalueof{/pgfplots/every axis title shift}]
      {\ref{grouplegend}};

  \end{tikzpicture}

\end{document}

Two-column plot with uninformative legend

Best Answer

By default, the entries you add using \addlegendentry are not expanded, so they all consist of just \colname at the time when the legend is called, which is outside the scope where \colname is defined. This can be fixed by using \addlegendentryexpanded{...} instead.

I've also taken the liberty to add a little more space between the legend entries (as described in How can I adjust the horizontal spacing between legend entries in PGFPlots?):

\documentclass[]{standalone}

\usepackage[svgnames]{xcolor}
\usepackage{pgfplots}
\usepackage{pgfplotstable}
\usepgfplotslibrary{groupplots}

\pgfplotsset{% global config
  compat=newest,
  every minor tick={very thin, gray},
  minor tick num=4,
  enlargelimits=0.02,
  group style={
    columns=2,
    xlabels at=edge bottom,
    ylabels at=edge left},
  every axis legend/.append style={
    legend cell align=left,
    legend columns=4
  }
}

\pgfplotstableread{
  Time      {Model A}   {Model G}   {Model Z}
  0         1           1           1
  1         1           2           2
  2         2           3           3
  3         3           4           4
  4         5           5           8
  5         8           6           10
  6         13          7           16
}\modeltable

\pgfplotstableread{
  Time      {Data 1}  {Data 2}
  0         1.3       2.3
  1         2.6       3.6
  2         3.8       4.8
  3         7.9       5.9
  4         6.3       7.3
  5         7.5       6.5
  6         9.0       8.9
}\datatable

\begin{document}

  \begin{tikzpicture}

    \begin{groupplot}[
      xlabel={Time},
      ylabel={Amplitude},
      every axis title shift=0,
      legend to name=grouplegend,
      legend style={/tikz/every even column/.append style={column sep=0.5cm}}
     ]

      \pgfplotsinvokeforeach{1,2}{%
        \nextgroupplot[title=Data $#1$]

        % Models
        \foreach \y in {1, 2, 3} {
          \addplot [smooth, dashed, color=DarkRed]
            table[x index=0, y index=\y] {\modeltable};

          \pgfplotstablegetcolumnnamebyindex{\y}\of{\modeltable}\to{\colname}
          \addlegendentryexpanded{\colname}
        }

        % Data
        \addplot [only marks, mark=o]
          table[x index=0, y index=#1] {\datatable};
        \addlegendentry {Data}
      }

    \end{groupplot}

    \node (dummytitle) at ($(group c1r1.north)!0.5!(group c2r1.north)$)
      [above]{};
    \node (title) at (dummytitle.north)
      [above, yshift=\pgfkeysvalueof{/pgfplots/every axis title shift}]
      {Experimental Data};

    \node (legend) at ($(group c1r1.south)!0.5!(group c2r1.south)$)
      [below, yshift=-2\pgfkeysvalueof{/pgfplots/every axis title shift}]
      {\ref{grouplegend}};

  \end{tikzpicture}

\end{document}

Related Solutions

[Tex/LaTex] plotting two time series with bounds

This happens because PGFPlots only uses one "stack" per axis: You're stacking the second confidence interval on top of the first. The easiest way to fix this is probably to use the approach described in "Is there an easy way of using line thickness as error indicator in a plot?": After plotting the first confidence interval, stack the upper bound on top again, using stack dir=minus. That way, the stack will be reset to zero, and you can draw the second confidence interval in the same fashion as the first:

\documentclass{standalone}
\usepackage{pgfplots, tikz}

\usepackage{pgfplotstable}

\pgfplotstableread{
temps   y_h y_h__inf    y_h__sup    y_f y_f__inf    y_f__sup    

1   0.237340    0.135170    0.339511    0.237653    0.135482    0.339823    
2   0.561320    0.422007    0.700633    0.165871    0.026558    0.305184    
3   0.694760    0.534205    0.855314    0.074856    -0.085698   0.235411    
4   0.728306    0.560179    0.896432    0.003361    -0.164765   0.171487    
5   0.711710    0.544944    0.878477    -0.044582   -0.211349   0.122184    
6   0.671241    0.511191    0.831291    -0.073347   -0.233397   0.086703    
7   0.621177    0.471219    0.771135    -0.088418   -0.238376   0.061540    
8   0.569354    0.431826    0.706882    -0.094382   -0.231910   0.043146    
9   0.519973    0.396571    0.643376    -0.094619   -0.218022   0.028783    
10  0.475121    0.366990    0.583251    -0.091467   -0.199598   0.016664    
}{\table}

\begin{document}
\begin{tikzpicture}

    \begin{axis}
    % y_h confidence interval
    \addplot [stack plots=y, fill=none, draw=none, forget plot]   table [x=temps, y=y_h__inf]   {\table} \closedcycle;
    \addplot [stack plots=y, fill=gray!50, opacity=0.4, draw opacity=0, area legend]   table [x=temps, y expr=\thisrow{y_h__sup}-\thisrow{y_h__inf}]   {\table} \closedcycle;
    % subtract the upper bound so our stack is back at zero
    \addplot [stack plots=y, stack dir=minus, forget plot, draw=none] table [x=temps, y=y_h__sup] {\table};

    % y_f confidence interval
    \addplot [stack plots=y, fill=none, draw=none, forget plot]   table [x=temps, y=y_f__inf]   {\table} \closedcycle;
    \addplot [stack plots=y, fill=gray!50, opacity=0.4, draw opacity=0, area legend]   table [x=temps, y expr=\thisrow{y_f__sup}-\thisrow{y_f__inf}]   {\table} \closedcycle;

    % the line plots (y_h and y_f)    
    \addplot [stack plots=false, very thick,smooth,blue]  table [x=temps, y=y_h]   {\table};
    \addplot [stack plots=false, very thick,smooth,blue]  table [x=temps, y=y_f]   {\table};
    \end{axis}

\end{tikzpicture}
\end{document}

[Tex/LaTex] How to apply nodes near coords to a single bar / to a single plot

That's a lot of questions in a single post. This site works best if you ask about a single issue per post, preferably in such a way that other people with similar problems have a chance of finding the question. I would suggest that for each question in your post, you open a new issue where you try to generalise and whittle down the problem in such a way that it is "googleable". For example, your first question could be phrased as "How do I apply nodes near coords to a single bar / to a single plot?".

That said, here are quick answers for your four questions:

You can specify the nodes near coords in the \addplot [...] options instead of in the \begin{axis}[...] options. That way, it will only apply for that plot.
See How can I add a zero line to a plot?
You can change the relevant entry in the table from 25--29 to \bfseries 25--29.
Set enlarge y limits={abs=1}, enlarge x limits=false (or similar).

Best Answer

Related Solutions

[Tex/LaTex] plotting two time series with bounds

[Tex/LaTex] How to apply nodes near coords to a single bar / to a single plot

Related Question