# Rectangle around data points in pgfplots

If I have some data points in a pgfplot, how can I draw a rectangle around them, with the rectangle using the same coordinate system as the points?

I've included an example which does not work below.

\begin{tikzpicture}[scale=1.5]
\begin{axis}[xlabel=x, ylabel=y]
(0,2)
(2,3)
(3,1)
};
\addplot[red, thick,rounded corners] (0,-1) rectangle (0,0);
\end{axis}
\end{tikzpicture}


(Why is there a cross not a rectangle?)

From the manual I would expect that using:

\addplot[red, thick,rounded corners] (axis cs: 0,-1) rectangle (axis cs: 0,0);


might force the rectangle to use the same coordinate system as the points, but it does not, the code no longer compiles.

-

If you want to add elements like that to an axis, don't use \addplot (you're not adding a plot, after all), but \draw, \fill or \node:

 \documentclass[a4paper, 11pt]{article}

\usepackage{pgfplots}
\pgfplotsset{compat=newest} % Makes the axis label placement prettier

\begin{document}
\begin{tikzpicture}
\begin{axis}[xlabel=x, ylabel=y, ymin=0]