[Tex/LaTex] How to modify a boxplot!? (mean, outliers, values: median, …)

boxplotpgfplots

I have some issues with my boxplot and I hope someone can help me to fix them.

Here my MWE:

\documentclass[a4paper]{scrbook}

\usepackage[utf8]{inputenc}                     
\usepackage{textcomp}                           
\usepackage[T1]{fontenc}                        
\usepackage[english,ngerman]{babel}
\usepackage[babel,german=quotes,threshold=1]{csquotes} 

\usepackage[language=autobib,
backend=biber %%%  !!!!
]{biblatex}

\usepackage{lmodern}                            
\usepackage{scrlayer-scrpage}                   
\usepackage{tikz}
\usepackage{pgfplots}
\usepackage{pgfplotstable}
\usepgfplotslibrary{statistics}
\pgfplotsset{compat=1.8}
\pgfplotsset{/pgf/number format/use comma} %%% does not work: comma instead of dot                                          
\usepackage{caption}
\usepackage{graphicx}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{document}
\begin{figure}
\textcolor{black!50}{\rule{\linewidth}{0.25pt}}
\centering
\scriptsize
\\[5ex]
\begin{tikzpicture}
  \begin{axis}
    [
    clip=false,
    boxplot/draw direction=y,
    boxplot/variable width,
    boxplot/every median/.style={black,very thick,solid},
    width=1.00\textwidth,
    height=0.33\textheight,
    ylabel style={align=center}, 
    ytick={0,1,2,3,4,5,6,7},
    y tick label style={align=right},
    yticklabels={0,1,2,3,4,5,6,7},
    xtick={0,1,2,3,4},
    x tick label style={align=center},
    xticklabels={,1,2,3,4}
    ]

    \node at (axis cs:0,0) [anchor=west] {\tiny (- - -)};
    \node at (axis cs:0,8) [anchor=west] {\tiny (+++)};

%%% MEAN %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    \draw[black, densely dotted]
      (axis cs:0, 5.50) coordinate (tmp)
      (current axis.west |- tmp) -- (current axis.east |- tmp);

      %%% Can the value "5,50" be displayed on the left side of the graph above he dotted line?


%%% 1 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    \addplot[
    mark=*,
    boxplot,
    boxplot prepared={
      average=5,
      lower whisker=2,
      lower quartile=4.5,
      median=5,
      upper quartile=6.5,
      upper whisker=7,
      sample size=3 
    },
    ] 
    coordinates {}
    node[right,font=\scriptsize] at (boxplot box cs: \boxplotvalue{average}, 0.95)
    {\boxplotvalue{average}};    
    ;


% 2 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    \addplot[
    mark=*, 
    boxplot,
    mark options={fill=white}, 
    boxplot prepared={
      average=6.25,
      lower whisker=5,
      lower quartile=6,
      median=6,
      upper quartile=7,
      upper whisker=7,
      sample size=3 
    },
    ] 
    coordinates {
    (2,1) % mark as "*"
    (2,4) % mark as "°"
    }
    node[right,font=\scriptsize] at (boxplot box cs: \boxplotvalue{average}, 0.95)
    {\boxplotvalue{average}};    
    ;


% 3 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    \addplot[
    mark=*, 
    boxplot,
    mark options={fill=white}, 
    boxplot prepared={
      average=6.3,
      lower whisker=5,
      lower quartile=6,
      median=6,
      upper quartile=7,
      upper whisker=7,
      sample size=3 
    },
    ] 
    coordinates {(3,4)}
    node[right,font=\scriptsize] at (boxplot box cs: \boxplotvalue{average}, 0.95)
    {\boxplotvalue{average}};    
    ;


% 4 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    \addplot[
    mark=*, 
    boxplot,
    boxplot prepared={
      average=5.50,
      lower whisker=4,
      lower quartile=5,
      median=6,
      upper quartile=6,
      upper whisker=7,
      sample size=3 
    },
    ] 
    coordinates {}
    node[right,font=\scriptsize] at (boxplot box cs: \boxplotvalue{average}, 0.95)
    {\boxplotvalue{average}};

  \end{axis}
\end{tikzpicture}
\textcolor{black!50}{\rule{\linewidth}{0.25pt}}
\caption{caption}
\end{figure}
\end{document}

How can I replace the "." with a "," as decimal separator? I thought \pgfplotsset{/pgf/number format/use comma} would be a solution!?

Extreme outliers are usually marked with a "*". How can I do so for the outlier with the coordinates (2,1)?

The mean over all the groups is 5.5. (dotted line) Is it possible to display this value above the dotted line on the left side of the graph?

Can the 50% quantile of the boxes be displayed? (left of each box)

Best Answer

I had expected a couple of these things to be a bit harder, but wasn't that bad.

As mentioned in a comment, \boxplotvalue{average} doesn't pass the number through the pgf number parser, so the /pgf/number format/use comma has no effect. Use \pgfmathprintnumber{\boxplotvalue{average}}.
One way of achieving this is to use scatter/classes. To the axis options add
```
scatter/classes={
  a={mark=star},
  b={mark=*}
}
```
To the options of the \addplot in question add
```
scatter,
scatter src=explicit symbolic,
```
And finally modify the coordinate stream to have
```
coordinates {
    (2,1) [a]
    (2,4) [b]
    };
```
To add a node above the start of a line from a to b one can use e.g. \draw (a) node[above right] {...} -- (b);. So in your case
```
\draw[black, densely dotted]
      (axis cs:0, 5.50) coordinate (tmp)
      (current axis.west |- tmp) node[above right] {\pgfmathprintnumber{5.5}}-- (current axis.east |- tmp);
```
(Some modification possibly needed, depending on exactly where you wanted that node, not sure I understood you correctly.)
The 50% quantile is just the median right, so you could use exactly the same method as you used for the average value. Do you want next to the middle of the box, or next to the median (as seen below) by the way?

That said, it's possible to modify how boxplot is drawn in order to add those two nodes by default. The styles that need modification is described in the manual, so I took most of the following from there, adding just two things indicated by comments:

\makeatletter
\pgfplotsset{
   boxplot/draw/average/.code={ % the bulk part of this is the default, found in the manual
      \draw [/pgfplots/boxplot/every average/.try]
      \pgfextra
      % do NOT use \draw[mark=*] plot coordinates because
      % boxplots uses the same plot handler to draw its
      % outliers.
      \pgftransformshift{%
      % basic level access to ’boxplot box cs’:
      \pgfplotsboxplotpointabbox
      {\pgfplotsboxplotvalue{average}}
      {0.5}%
    }%
    \pgfuseplotmark{\tikz@plot@mark}%
    \endpgfextra
    ;
    % the following line is the only new addition
    \node[right,font=\scriptsize] at (boxplot box cs: \boxplotvalue{average}, 0.95) {\pgfmathprintnumber{\boxplotvalue{average}}};
},
boxplot/draw/median/.code={
   \draw [/pgfplots/boxplot/every median/.try]
       (boxplot box cs:\pgfplotsboxplotvalue{median},0)
         % the following line is the only difference from the default definition
         node[left] {\pgfmathprintnumber{\pgfplotsboxplotvalue{median}}}
        --
        (boxplot box cs:\pgfplotsboxplotvalue{median},1);
  },
}
\makeatother

In the code below I just added this just before \begin{tikzpicture}. However, if you have multiple boxplots that all should have the same style, it's probably better to either move it to the preamble, or make a new style.

\documentclass[a4paper]{scrbook}

\usepackage[utf8]{inputenc}                     
\usepackage[T1]{fontenc}                        

\usepackage{pgfplotstable} % loads pgfplots which loads tikz which loads graphicx
\usepgfplotslibrary{statistics}
\pgfplotsset{compat=1.8}
\pgfplotsset{/pgf/number format/use comma} 
\usepackage{caption}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{document}
\begin{figure}
\textcolor{black!50}{\rule{\linewidth}{0.25pt}}
\centering
\scriptsize
\\[5ex]
\makeatletter
\pgfplotsset{
   boxplot/draw/average/.code={ % the bulk part of this is the default, found in the manual
      \draw [/pgfplots/boxplot/every average/.try]
      \pgfextra
      % do NOT use \draw[mark=*] plot coordinates because
      % boxplots uses the same plot handler to draw its
      % outliers.
      \pgftransformshift{%
      % basic level access to ’boxplot box cs’:
      \pgfplotsboxplotpointabbox
      {\pgfplotsboxplotvalue{average}}
      {0.5}%
    }%
    \pgfuseplotmark{\tikz@plot@mark}%
    \endpgfextra
    ;
    % the following line is the only new addition
    \node[right,font=\scriptsize] at (boxplot box cs: \boxplotvalue{average}, 0.95) {\pgfmathprintnumber{\boxplotvalue{average}}};
},
boxplot/draw/median/.code={
   \draw [/pgfplots/boxplot/every median/.try]
       (boxplot box cs:\pgfplotsboxplotvalue{median},0)
         % the following line is the only difference from the default definition
         node[left] {\pgfmathprintnumber{\pgfplotsboxplotvalue{median}}}
        --
        (boxplot box cs:\pgfplotsboxplotvalue{median},1);
  },
}
\makeatother
\begin{tikzpicture}
  \begin{axis}
    [
    clip=false,
    boxplot/draw direction=y,
    boxplot/variable width,
    boxplot/every median/.style={black,very thick,solid},
    width=1.00\textwidth,
    height=0.33\textheight,
    ylabel style={align=center}, 
    ytick={0,1,2,3,4,5,6,7},
    y tick label style={align=right},
    yticklabels={0,1,2,3,4,5,6,7},
    xtick={0,1,2,3,4},
    x tick label style={align=center},
    xticklabels={,1,2,3,4},
    scatter/classes={
      a={mark=star},
      b={mark=*}
    }
    ]

    \node at (axis cs:0,0) [anchor=west] {\tiny (- - -)};
    \node at (axis cs:0,8) [anchor=west] {\tiny (+++)};

%%% MEAN %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    \draw[black, densely dotted]
      (axis cs:0, 5.50) coordinate (tmp)
      (current axis.west |- tmp) node[above right] {\pgfmathprintnumber{5.5}}-- (current axis.east |- tmp);

      %%% Can the value "5,50" be displayed on the left side of the graph above he dotted line?


%%% 1 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    \addplot[
    mark=*,
    boxplot,
    boxplot prepared={
      average=5,
      lower whisker=2,
      lower quartile=4.5,
      median=5,
      upper quartile=6.5,
      upper whisker=7,
      sample size=3 
    },
    ] 
    coordinates {};


% 2 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    \addplot[
    boxplot,
    scatter,
    scatter src=explicit symbolic,
    mark options={fill=white}, 
    boxplot prepared={
      average=6.25,
      lower whisker=5,
      lower quartile=6,
      median=6,
      upper quartile=7,
      upper whisker=7,
      sample size=3 
    },
    ] 
    coordinates {
    (2,1) [a]
    (2,4) [b]
    };



% 3 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    \addplot[
    mark=*, 
    boxplot,
    mark options={fill=white}, 
    boxplot prepared={
      average=6.3,
      lower whisker=5,
      lower quartile=6,
      median=6,
      upper quartile=7,
      upper whisker=7,
      sample size=3 
    },
    ] 
    coordinates {(3,4)};


% 4 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    \addplot[
    mark=*, 
    boxplot,
    boxplot prepared={
      average=5.50,
      lower whisker=4,
      lower quartile=5,
      median=6,
      upper quartile=6,
      upper whisker=7,
      sample size=3 
    },
    ] 
    coordinates {};

  \end{axis}
\end{tikzpicture}
\textcolor{black!50}{\rule{\linewidth}{0.25pt}}
\caption[caption]{caption}
\end{figure}
\end{document}

Related Solutions

[Tex/LaTex] pgfplots – draw boxplot without outliers

If you add the following code snippet to your preamble, you can use hide outliers to locally disable plotting the outliers:

\makeatletter
\pgfplotsset{
    boxplot/hide outliers/.code={
        \def\pgfplotsplothandlerboxplot@outlier{}%
    }
}
\makeatother

\documentclass{article}
\usepackage{pgfplots}
\usepgfplotslibrary{statistics}
\begin{document}

\makeatletter
\pgfplotsset{
    boxplot/hide outliers/.code={
        \def\pgfplotsplothandlerboxplot@outlier{}%
    }
}
\makeatother


\begin{tikzpicture}
\begin{axis}[y=1cm, try min ticks=2]
\addplot+[boxplot]
table[row sep=\\,y index=0] {
data\\
1\\ 2\\ 1\\ 5\\ 4\\ 10\\
7\\ 10\\ 9\\ 8\\ 9\\ 9\\
21\\
};
\end{axis}
\end{tikzpicture}

\begin{tikzpicture}
\begin{axis}[y=1cm, try min ticks=2]
% somewhen the simple statement of `hide outliers` broke.
% Now the full path to the style needs to be written.
\addplot+[boxplot, /pgfplots/boxplot/hide outliers]
table[row sep=\\,y index=0] {
data\\
1\\ 2\\ 1\\ 5\\ 4\\ 10\\
7\\ 10\\ 9\\ 8\\ 9\\ 9\\
21\\
};
\end{axis}
\end{tikzpicture}


\end{document}

[Tex/LaTex] Read boxplot prepared values from a table

The table in an \addplot command using the boxplot plot type is only used for providing raw data (if using boxplot) or outlier data (if using boxplot prepared), but not the box parameters. Those always need to be provided directly using the boxplot prepared={...} options.

You can, however, write a couple of wrapper styles that read the values from a table and set the required keys. That would allow you to write something like

\addplot+[
  boxplot prepared from table={
    table=\datatable,
    lower whisker=lw,
    upper whisker=uw,
    lower quartile=lq,
    upper quartile=uq,
    median=med
  }, boxplot prepared
  ]
  coordinates {};
\addplot+[
  boxplot prepared from table={
    table=\datatable,
    row=1,
    lower whisker=lw,
    upper whisker=uw,
    lower quartile=lq,
    upper quartile=uq,
    median=med
  }, boxplot prepared
  ]
  coordinates {};

to get

\documentclass[crop=false]{standalone}
\usepackage{pgfplotstable}
\pgfplotsset{compat=1.8}
\usepgfplotslibrary{statistics}
\makeatletter
\pgfplotsset{
    boxplot prepared from table/.code={
        \def\tikz@plot@handler{\pgfplotsplothandlerboxplotprepared}%
        \pgfplotsset{
            /pgfplots/boxplot prepared from table/.cd,
            #1,
        }
    },
    /pgfplots/boxplot prepared from table/.cd,
        table/.code={\pgfplotstablecopy{#1}\to\boxplot@datatable},
        row/.initial=0,
        make style readable from table/.style={
            #1/.code={
                \pgfplotstablegetelem{\pgfkeysvalueof{/pgfplots/boxplot prepared from table/row}}{##1}\of\boxplot@datatable
                \pgfplotsset{boxplot/#1/.expand once={\pgfplotsretval}}
            }
        },
        make style readable from table=lower whisker,
        make style readable from table=upper whisker,
        make style readable from table=lower quartile,
        make style readable from table=upper quartile,
        make style readable from table=median,
        make style readable from table=lower notch,
        make style readable from table=upper notch
}
\makeatother


\pgfplotstableread{
    lw lq med  uq uw
     5  7 8.5 9.5 10
     4  5 6.5 8.5 9.5
}\datatable


\begin{document}
\begin{tikzpicture}
\begin{axis}[boxplot/draw direction=y]
  \addplot+[
  boxplot prepared from table={
    table=\datatable,
    lower whisker=lw,
    upper whisker=uw,
    lower quartile=lq,
    upper quartile=uq,
    median=med
  }, boxplot prepared
  ]
  coordinates {};
  \addplot+[
  boxplot prepared from table={
    table=\datatable,
    row=1,
    lower whisker=lw,
    upper whisker=uw,
    lower quartile=lq,
    upper quartile=uq,
    median=med
  }, boxplot prepared
  ]
  coordinates {};
\end{axis}
\end{tikzpicture}
\end{document}

Best Answer

Related Solutions

[Tex/LaTex] pgfplots – draw boxplot without outliers

[Tex/LaTex] Read boxplot prepared values from a table

Related Question