# TikZ PGFPlots Boxplots - Two labels (agree & disagree) on x axis

I want to visualise the results of a questionnaire using Boxplots. I am using TikZ with PGFPlots. I would like to label the left of the x axis with "Strongly disagree" and the right with "Strongly agree" instead of just labelling the whole axis with "Approval". This is also how the questions on the questionnaire looked like for the participants. How can I do this? This is my code:

\documentclass{scrartcl}
\usepackage{tikz}
\usepackage{pgfplots}
\usepgfplotslibrary{statistics}
\pgfplotsset{compat=1.8}

\begin{document}

\begin{figure}
\centering
\begin{tikzpicture}
\begin{axis}
[
xlabel={Approval},
ytick={0},
width = 1\textwidth,
height = 0.15\textheight,
xmin=0.25,
xmax=7.75,
xtick={1,2,3,4,5,6,7},
boxplot/every median/.style={red, thick}
]
mark=*,
boxplot prepared={
average= 3.7,
median= 4,
upper quartile= 5,
lower quartile= 3,
upper whisker= 6,
lower whisker= 1
},
] coordinates {};
\end{axis}
\end{tikzpicture}
\end{figure}

\end{document}


There are several different approaches one could take. I'm assuming here you also want the numbers, and add the new labels using extra x ticks and labels. There are just a few extra lines in the axis options, see also the comments in the code.

\documentclass{scrartcl}
\usepackage{pgfplots}
\usepgfplotslibrary{statistics}
\pgfplotsset{compat=1.8}

\begin{document}

\begin{figure}
\centering
\begin{tikzpicture}
\begin{axis}
[
xlabel={Approval},
ytick={0},
width = 1\textwidth,
height = 0.15\textheight,
xmin=0.25,
xmax=7.75,
xtick={1,2,3,4,5,6,7},
boxplot/every median/.style={red, thick},
extra x ticks={1, 7}, % x values where you want the labels
extra x tick labels={Strongly disagree, Strongly agree}, % and the corresponding labels
extra x tick style={
yshift=-15pt, % move them down a bit
tickwidth=0 % and remove the ticks (small vertical lines)
}
]
mark=*,
boxplot prepared={
average= 3.7,
median= 4,
upper quartile= 5,
lower quartile= 3,
upper whisker= 6,
lower whisker= 1
},
] coordinates {};
\end{axis}
\end{tikzpicture}
\end{figure}

\end{document}