Can I use pgfplots to make a boxplot

Question

My current plotting tool for my papers is pgfplots for nice consistent plots. Now I would like to add a boxplot. Is this possible with help of pgfplots, or any helper package?

Answer 1

PGFPlots supports boxplots natively as of version 1.8 See Boxplot in latex for an example.

The remainder of this answer should be considered obsolete.

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There is a much improved version of this code at Simpler boxplots in pgfplots - is this possible?. It allows creating box plots with a single command, and adds much more flexibility to the data format and the plot styles:

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Original answer:

Not out of the box, and you'd have to do the quantile calculations outside of PGFplots, but then you can draw box plots with a bit of style trickery.

This code

\begin{axis} [enlarge x limits=0.5,xtick=data]
    \addplot [box plot median] table {testdata.dat};
    \addplot [box plot box] table {testdata.dat};
    \addplot [box plot top whisker] table {testdata.dat};
    \addplot [box plot bottom whisker] table {testdata.dat};
\end{axis}

can generate this plot

if testdata.dat is of the form

index median box_top box_bottom whisker_top whisker_bottom

Here's a full compilable example:

\documentclass{article}
\usepackage{pgfplots}
\usepackage{filecontents}

\begin{filecontents}{testdata.dat}
0 1 1.2 0.4 1.5 0.2
1 2 2.3 1.5 2.7 1
2 0.7 1.4 0.5 1.9 0.1
\end{filecontents}

\pgfplotsset{
    box plot/.style={
        /pgfplots/.cd,
        black,
        only marks,
        mark=-,
        mark size=1em,
        /pgfplots/error bars/.cd,
        y dir=plus,
        y explicit,
    },
    box plot box/.style={
        /pgfplots/error bars/draw error bar/.code 2 args={%
            \draw  ##1 -- ++(1em,0pt) |- ##2 -- ++(-1em,0pt) |- ##1 -- cycle;
        },
        /pgfplots/table/.cd,
        y index=2,
        y error expr={\thisrowno{3}-\thisrowno{2}},
        /pgfplots/box plot
    },
    box plot top whisker/.style={
        /pgfplots/error bars/draw error bar/.code 2 args={%
            \pgfkeysgetvalue{/pgfplots/error bars/error mark}%
            {\pgfplotserrorbarsmark}%
            \pgfkeysgetvalue{/pgfplots/error bars/error mark options}%
            {\pgfplotserrorbarsmarkopts}%
            \path ##1 -- ##2;
        },
        /pgfplots/table/.cd,
        y index=4,
        y error expr={\thisrowno{2}-\thisrowno{4}},
        /pgfplots/box plot
    },
    box plot bottom whisker/.style={
        /pgfplots/error bars/draw error bar/.code 2 args={%
            \pgfkeysgetvalue{/pgfplots/error bars/error mark}%
            {\pgfplotserrorbarsmark}%
            \pgfkeysgetvalue{/pgfplots/error bars/error mark options}%
            {\pgfplotserrorbarsmarkopts}%
            \path ##1 -- ##2;
        },
        /pgfplots/table/.cd,
        y index=5,
        y error expr={\thisrowno{3}-\thisrowno{5}},
        /pgfplots/box plot
    },
    box plot median/.style={
        /pgfplots/box plot
    }
}

\begin{document}
\begin{tikzpicture}
\begin{axis} [enlarge x limits=0.5,xtick=data]
    \addplot [box plot median] table {testdata.dat};
    \addplot [box plot box] table {testdata.dat};
    \addplot [box plot top whisker] table {testdata.dat};
    \addplot [box plot bottom whisker] table {testdata.dat};
\end{axis}
\end{tikzpicture}
\end{document}

Answer 2

For every point more than 3/2 times the interquartile range from the end of a box, is a dot. The only special optional arguments, beside all other which are valid for drawing lines and filling areas, are IQLfactor, barwidth, and arrowlength, where the latter is a factor which is multiplied with the barwidth for the line ends. The IQLfactor, preset to 1.5, defines the area for the outliers.

Run it with xelatex

\documentclass{article}
\usepackage{pst-plot}
\begin{document}

\begin{pspicture}(-1,-1)(12,14)
\psset{yunit=0.1,fillstyle=solid}
\psaxes[dy=1cm,Dy=10,ticksize=4pt 0,axesstyle=frame](0,0)(12,130)
\rput(1,0){\psBoxplot[fillcolor=red!30]{
   100 90 120 115 120 110 100 110 100 90 100 100 120 120 120}}\rput(1,105){2001}
\rput(3,0){\psBoxplot[arrowlength=0.5,fillcolor=blue!30]{
  90 120 115 116 115 110 90 130 120 120 120 85 100 130 130}}\rput(3,107){2008}
\rput(5,0){\psBoxplot[barwidth=40pt,arrowlength=1.2,fillcolor=red!30]{
  35 70 90 60 100 60 60 80 80 60 50 55 90 70 70}}\rput(5,65){2001}
\rput(7,0){\psBoxplot[barwidth=40pt,fillcolor=blue!30]{
  60 65 60 75 75 60 50 90 95 60 65 45 45 60 90}}\rput(7,65){2008}
\rput(9,0){\psBoxplot[fillcolor=red!30]{
  20 20 25 20 15 20 20 25 30 20 20 20 30 30 30}}\rput(9,22){2001}
\rput(11,0){\psBoxplot[fillcolor=blue!30,linestyle=dashed]{
  20 30 20 35 35 20 20 60 50 20 35 15 30 20 40}}\rput(11,25){2008}
\end{pspicture}
\end{document}

Answer 3

If you use R, you can output the boxplot using tikzDevice.

Here's an example:

library(tikzDevice)
tikz('normal.tex', standAlone = TRUE, width=5, height=5)
boxplot(mpg~cyl,data=mtcars, main="Car Milage Data",
+    xlab="Number of Cylinders", ylab="Miles Per Gallon") 
dev.off()

Answer 4

QtiPlot is a free program that can take your spreadsheet data and create a box plot with a consistent look. You can change the title, x-axis, etc., and then export the image into a .tex file thereby generating all the code from \begin{tikzpicture} to \end{tikzpicture}. Copy that code into your LaTeX document. Here is what I generated from some sample data.

Answer 5

I am not aware of any easy-to-use packages for producing box plots in pgfplots but this TeXample example and this topic at LaTeX Community show that it's not too hard to produce one.