[Tex/LaTex] Combine markers in legend entry

legendpgfplotstikz-pgf

I've searched for this online and on this website but couldn't find anything. I would like to place two markers side by side in a legend entry. MWE:

\documentclass[tikz,border=0pt]{standalone} 
\usepackage{pgfplots}
\begin{document}
\begin{tikzpicture}
    \begin{axis}[
        xlabel=$x$,
        ylabel={$y$}
    ]
    \addplot [black,domain=-6:6, samples=100,unbounded coords=jump]{x^2 - x +4};
    \addplot [black,domain=-6:6, samples=100,unbounded coords=jump,forget plot]{x^4 - x +4};
    \addplot [only marks,mark=*]{x^2 - x +4};
    \addplot [only marks,mark=square*]{x^4 - x +4};
    \legend{$Analytical$,$Numerical$,$Numerical$}
    \end{axis}
\end{tikzpicture}
\end{document}

Here is a screenshot with the output. I've overlaid what I am trying to achieve. If this is unclear let me know and I will add clarification.

Best Answer

You can define a new style for a legend entry like combo legend below. That style is used in a \addlegendimage, and forget plot is added to the two existing plots, so they are not included in the legend.

Unrelated note: "Analytical" and "Numerical" are not math expressions, so don't write them in $ ... $ . If you want the legend entries in italics, use legend style={font=\itshape}.

\documentclass[tikz,border=0pt]{standalone} 
\usepackage{pgfplots}
\begin{document}
\begin{tikzpicture}
    \begin{axis}[
        xlabel=$x$,
        ylabel={$y$},
        % define plot styles, for convenience
        num1/.style={black,only marks,mark=*},
        num2/.style={black,only marks,mark=square*},
        % make new legend style
        combo legend/.style={
          legend image code/.code={
            \draw [/pgfplots/num1] plot coordinates {(1mm,0cm)};
            \draw plot coordinates {(2.5mm,-3pt)} node {,};
            \draw [/pgfplots/num2] plot coordinates {(4.5mm,0cm)};
          }
        }
    ]
    \addplot [black,domain=-6:6, samples=100,unbounded coords=jump]{x^2 - x +4};
    \addplot [black,domain=-6:6, samples=100,unbounded coords=jump,forget plot]{x^4 - x +4};

    % note forget plot, which means the plot is not included in legend
    \addplot [forget plot, num1]{x^2 - x +4};
    \addplot [forget plot, num2]{x^4 - x +4};

    % adds new "fake plot" that is included in legend
    \addlegendimage{combo legend}

    \legend{Analytical,Numerical}
    \end{axis}
\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 hide empty (value 0) ybars with pgfplots

You can use

 y filter/.expression={y==0 ? nan : y}

in the options of \addplot.

\documentclass{article}

% ---------------------------------- tikz
\usepackage{pgfplots}          % to print charts
\pgfplotsset{compat=1.12}

\begin{document}

\begin{figure}
  \centering
  \begin{tikzpicture}
    \begin{axis} [
      % general
      ybar,
      scale only axis,
      height=0.5\textwidth,
      width=1.2\textwidth,
      ylabel={\# Dots},
      nodes near coords,
      xlabel={Variation},
      xticklabel style={
        rotate=90,
        anchor=east,
      },
      %enlarge x limits={abs value={3}},
      ]
      \addplot+[y filter/.expression={y==0 ? nan : y}] table [
        x=grade,
        y=value,
      ] {
grade   value
-11 0
-10 0
-9  0
-8  0
-7  0
-6  0
-5  3
-4  1
-3  2
-2  15
-1  11
0   179
1   8
2   1
3   0
4   1
5   2
6   0
7   0
8   0
9   0
10  0
11  0
      };
    \end{axis}
  \end{tikzpicture}
\end{figure}
\end{document}

Best Answer

Related Solutions

[Tex/LaTex] plotting two time series with bounds

[Tex/LaTex] How to hide empty (value 0) ybars with pgfplots

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