Put pgfplots axis on the margin of printable text area

Question

In order to gain some horizontal space (e.g. to put two plots next to each other) and because this is the least ugly solution for that I would like to be able to put the axis line of a pgfplot exactly on the border where text would begin (or end) in a line. (in the MWE below: it should lie directly on the frame of the text area). Shifting them manually by trying out appropriate values (as done in the MWE) is not the ideal solution.

\documentclass{article}
\usepackage{showframe}
\usepackage{pgfplots}

\newcommand{\myfig}{
    \begin{tikzpicture}
    \begin{axis}[height=5cm,width=7cm]
    \addplot {2^x};
    \end{axis}
    \end{tikzpicture}
    }

\begin{document}
\myfig % too much space on the left

\hspace{-12.5mm}\myfig % correct (but manual) placement

\flushright
\myfig % too much space on the right

\myfig\hspace*{-3.3mm} % correct (but manual) placement
\end{document}

I know I must work with anchors but later I am working in floating environments and cannot give an exact (vertical) position related to the page. Who knows how to do it?

Answer 1

trim axis left and trim axis right is what you're looking for. These options can be added to the arguments of the tikzpicture (not the axis), and changes the bounding box so that everything left (right) of current axis.south west (current axis.south east) is trimmed away.

Note that in your example I also added some % in the \myfig macro to avoid spurious spaces (see e.g. Why the end-of-line % in macro definitions?), and I added a \noindent to remove the standard paragraph indent.

\documentclass{article}
\usepackage{showframe}
\usepackage{pgfplots}

\newcommand{\myfig}[1]{%
    \begin{tikzpicture}[#1]
    \begin{axis}[height=5cm,width=7cm]
    \addplot {2^x};
    \end{axis}
    \end{tikzpicture}%
    }

\begin{document}
\noindent\myfig{trim axis left}


\flushright
\myfig{trim axis right}
\end{document}