[Tex/LaTex] Positioning pgfplots axis in tikzpicture

graphicspgfplotstikz-pgf

I want to put a pgfplots plot beside several other pdf images that I import into my document, but I can't figure out how to position the pgfplots axis in the larger tikzpicture:

\documentclass{article}

\usepackage{graphicx}
\usepackage{pgfplots}
\pgfplotsset{compat=1.9}

\begin{document}
\begin{figure*}

  \begin{center}
    \begin{tikzpicture}

       \node[anchor=south west] (img) at (0,0) 
            {\includegraphics[width=0.3\linewidth]{1.pdf}};
       \node[anchor=south west] 
            at (0.01\linewidth,0.01\linewidth) {a};        

       \node[anchor=south west] (img) at (0.33\linewidth,0) 
            {\includegraphics[width=0.3\linewidth]{1.pdf}};
       \node[anchor=south west] 
            at (0.34\linewidth,0.01\linewidth) {b}; 

       \begin{axis}[width=0.45\linewidth, yticklabels={}]
         \addplot [const plot, fill=red] 
                  table [x index=0, y index=1]
                  {hist.txt}
         \closedcycle;  
       \end{axis}

    \end{tikzpicture}
  \end{center}

  \caption{\label{detdemo}An example of my output}
\end{figure*}
\end{document}

here is the example output:
example output

The axis seems to begin from the (0,0) of the tikzpicture.

I wanted to see how I can position this axis after the second picture? Such that its bottom left corner is on (0.66\linewidth,0).

Best Answer

You can define the coordinate for the lower left corner of the axis with the at key, 

at={(0.66\linewidth,0)}

Add this to the axis options.

enter image description here

\documentclass{article}

\usepackage{graphicx}
\usepackage{pgfplots}
\pgfplotsset{compat=1.9}

\begin{document}
\begin{figure*}

  \begin{center}
    \begin{tikzpicture}

       \node[anchor=south west] (img) at (0,0) 
            {\includegraphics[width=0.3\linewidth]{example-image-a}};
       \node[anchor=south west] 
            at (0.01\linewidth,0.01\linewidth) {a};        

       \node[anchor=south west] (img) at (0.33\linewidth,0) 
            {\includegraphics[width=0.3\linewidth]{example-image-b}};
       \node[anchor=south west] 
            at (0.34\linewidth,0.01\linewidth) {b}; 

       \begin{axis}[width=0.45\linewidth, yticklabels={},at={(0.66\linewidth,0)}]
         \addplot [const plot, fill=red] 
                  {x}
         \closedcycle;  
       \end{axis}

    \end{tikzpicture}
  \end{center}

  \caption{\label{detdemo}An example of my output}
\end{figure*}
\end{document}
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