legendpgfplots
I'm attempting to remove or 'turn off' the legend border in pgfplots, but I can't seem to figure out how to do it. I assume it will look something like this:
\begin{axis}[ legend style={?}]
where ? is a property related to the legend border (or box) that I can't seem to find. The pgfplots help is really great, but I haven't seen this addressed anywhere. Does anyone know how to accomplish this simple task?
You could perhaps use the \addlegendimage command, as in this discussion from the pgfplots-features mailing list.
An example, with a small \hspace hack to place the title more centered in the legend box:
\documentclass{standalone}
\usepackage{pgfplots}
\begin{document}
\begin{tikzpicture}
\begin{axis}[legend pos=south east]
\addlegendimage{empty legend}
\addplot {sqrt(x)};
\addplot {ln(x)};
\addlegendentry{\hspace{-.6cm}\textbf{A title}}
\addlegendentry{$\sqrt{x}$}
\addlegendentry{$\ln{x}$}
\end{axis}
\end{tikzpicture}
\end{document}
For variety, here's a couple of more manual approaches. In each case the legend and title are separate entities, and the frame drawn afterwards.
\documentclass[border=5mm,tikz]{standalone}
\usepackage{pgfplots}
\usetikzlibrary{fit}
\begin{document}
\begin{tikzpicture}
\begin{axis}[legend style={at={(rel axis cs:0.9,0.1)},above left,name=legend,draw=none}]
\addplot {sqrt(x)};
\addplot {ln(x)};
\addlegendentry{$\sqrt{x}$}
\addlegendentry{$\ln{x}$}
\end{axis}
\node [above,font=\bfseries] (legendtitle) at (legend.north) {Legend title};
\node [fit=(legendtitle)(legend),draw,inner sep=0pt] {};
\end{tikzpicture}
\begin{tikzpicture}
\begin{axis}[legend style={draw=none,legend to name=leg}]
\addplot {sqrt(x)};
\addplot {ln(x)};
\addlegendentry{$\sqrt{x}$}
\addlegendentry{$\ln{x}$}
% place legend
\node [above left] (L) at (rel axis cs:0.9,0.1) {\ref{leg}};
% Add title
\node [above,font=\bfseries] (LT) at (L.north) {Legend title};
% if needed, add frame
\node [fit=(L)(LT),draw,inner sep=0pt] {};
\end{axis}
\end{tikzpicture}
\end{document}
You can add fill=none to the legend style key as in this approach.
\documentclass[11pt]{article}
\usepackage[T1]{fontenc}
\usepackage{pgfplots}
\pgfplotsset{compat=1.9}
\begin{document}
\begin{tikzpicture}
\begin{axis}[
legend style={fill=none}
]
\addplot {x};
\addlegendentry{$x$};
\end{axis}
\end{tikzpicture}
\end{document}
Best Answer
Try
That looks like it might be asking for no legend to be drawn at all but actually it just applies to the rectangle around the legend.