[Tex/LaTex] Drawing solid-circle or dots in legends

pgfplotstikz-pgf

I'm trying to create plot with solid circles in the legend. Please see the image below for what I've got so far:

I'm unable to get my legend right, ideally I would like to draw solid red circle with label Maxima and solid blue circle with label Minima. However, I'm not sure how to create solid circles in legend.

Please see my code below:

\begin{tikzpicture}
  \begin{axis}[
    trig format plots=rad,
    axis lines = middle,
    enlargelimits,
    clip=false,
    legend entries={Minima,Maxima}
    ]
    \addplot[domain=-2*pi:2*pi,samples=200,black] {sin(x)};
    \fill[red] (axis cs: 0.5*pi,1.0) circle[radius=3pt];
    \fill[red] (axis cs: -1.5*pi,1.0) circle[radius=3pt];
    \fill[blue] (axis cs: -0.5*pi,-1.0) circle[radius=3pt];
    \fill[blue] (axis cs: 1.5*pi,-1.0) circle[radius=3pt];
    \draw[dotted,red!80] (axis cs: -1.5*pi,1.1) -- (axis cs: -1.5*pi,0);
    \draw[dotted,red!80] (axis cs: 0.5*pi,1.1) -- (axis cs: 0.5*pi,0);
    \draw[dotted,blue!80] (axis cs: 1.5*pi,-1.1) -- (axis cs: 1.5*pi,0.0);
    \draw[dotted,blue!80] (axis cs: -0.5*pi,-1.1) -- (axis cs: -0.5*pi,0.0);
    \addlegendimage{mark=ball,ball color=red,draw=red}
    \addlegendimage{mark=ball,ball color=blue,draw=blue}
  \end{axis}
\end{tikzpicture}

Any help or suggestions would be greatly appreciated.

Best Answer

For this simple case, you can fake it

\begin{tikzpicture}
\begin{axis}[
    trig format plots=rad,
    axis lines = middle,
    enlargelimits,
    clip=false,
    legend entries={Maxima,Minima}
    ]
    \addplot[domain=-2*pi:2*pi,samples=101, black,forget plot] {sin(x)};
    \addplot[domain=-3*pi/2:pi/2,samples=2,only marks,mark options=red] {sin(x)<0?NaN:sin(x)};
    \addplot[domain=-pi/2:3*pi/2,samples=2,only marks,mark options=blue] {sin(x)>0?NaN:sin(x)};
  \end{axis}
\end{tikzpicture}

Related Solutions

PGFPlots – How to Plot Two Time Series with Bounds Using PGFPlots

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] TikZ: Drawing an arc from an intersection to an intersection

A solution which allows to draw intersection segments of any two intersections is available as tikz library fillbetween.

This library works as general purpose tikz library, but it is shipped with pgfplots and you need to load pgfplots in order to make it work:

\documentclass{standalone}

\usepackage{tikz}
\usepackage{pgfplots}
\usetikzlibrary{fillbetween}

\begin{document}

\begin{tikzpicture}

\draw [name path=red,red] (120:1.06) circle (1.9);
%\draw [name path=yellow,yellow] (0:1.06) circle (2.12);
\draw [name path=green,green!50!black] (0:0.77) circle (2.41);
\draw [name path=blue,blue] (0:0) circle (1.06);

% substitute this temp path by `\path` to make it invisible:
\draw[name path=temp1, intersection segments={of=red and blue,sequence=L1}];
\draw[red,-stealth,ultra thick, intersection segments={of=temp1 and green,sequence=L3}];

\end{tikzpicture}

\end{document}

enter image description here

The key intersection segments is described in all detail in the pgfplots reference manual section "5.6.6 Intersection Segment Recombination"; the key idea in this case is to

create a temporary path temp1 which is the first intersection segment of red and blue, more precisely, it is the first intersection segment in the Left argument in red and blue : red. This path is drawn as thin black path. Substitute its \draw statement by \path to make it invisible.
Compute the desired intersection segment by intersecting temp1 and green and use the correct intersection segment. By trial and error I figured that it is the third segment of path temp1 which is written as L3 (L = left argument in temp1 and green and 3 means third segment of that path).

The argument involves some trial and error because fillbetween is unaware of the fact that end and startpoint are connected -- and we as end users do not see start and end point.

Note that you can connect these path segments with other paths. If such an intersection segment should be the continuation of another path, use -- as before the first argument in sequence. This allows to fill paths segments:

\documentclass{standalone}

\usepackage{tikz}
\usepackage{pgfplots}
\usetikzlibrary{fillbetween}

\begin{document}

\begin{tikzpicture}

\draw [name path=red,red] (120:1.06) circle (1.9);
%\draw [name path=yellow,yellow] (0:1.06) circle (2.12);
\draw [name path=green,green!50!black] (0:0.77) circle (2.41);
\draw [name path=blue,blue] (0:0) circle (1.06);

% substitute this temp path by `\path` to make it invisible:
\draw[name path=temp1, intersection segments={of=red and blue,sequence=L1}];
\draw[red,fill=blue,-stealth,ultra thick, intersection segments={of=temp1 and green,sequence=L3}]  
    [intersection segments={of=temp1 and green, sequence={--R2}}]
;

\end{tikzpicture}

\end{document}

enter image description here

Best Answer

Related Solutions

PGFPlots – How to Plot Two Time Series with Bounds Using PGFPlots

[Tex/LaTex] TikZ: Drawing an arc from an intersection to an intersection

Related Question