[Tex/LaTex] How to do a shift/offset of ycomb or ybar **in y-direction** without stacking in pgfplots

bar chartpgfplots

I am looking for a way to shift the reference bars in an XRD plot in order to be able to compare two or more plots in the same axis environment but have the references only where they apply.
This should be equivalent to the existing bar shift key but in the direction of the bar plot, e.g. an easy way of adjusting the minimum value of the bar plot or the ycomb.

My minimum example contains two analysis plots and the references which are just coordinates in a different text file. I would want to shift the purple one upwards to the second plot.
This is what it looks like now: MWE_ycomb. 

\documentclass[]{article}

\usepackage{textcomp}
\usepackage{chemmacros}

% % % Plotting % % %
\usepackage{tikz}
\usepackage{pgfplots}
\usepackage{pgfplotstable}
\usetikzlibrary{plotmarks}
\pgfplotsset{compat=1.10}

\begin{document}

    \begin{figure}[htb]
        \centering
            \begin{tikzpicture}
                \begin{axis}[
                width = 14 cm,
                height = 6 cm,
                xlabel={2$\theta$ (\textdegree)},
                axis x line=bottom,
                ylabel={intensity (a.\,u.)},
                axis y line=left,
                tick align=outside,
                xmin=10,
                xmax=80,
                ymin=0,
                yticklabels= ,
                scaled ticks=false,
                ]                   
        % XRD
        \axispath\draw  (500,500) node[anchor=west, green!60!black] {\footnotesize{\ch{La2CuO4} (\#80-0579)}}
        (500,450) node[anchor=west, purple] {\footnotesize{\ch{La2O2CO3} (\#48-1113)}}
        (0,80) node[anchor=west, black] {\footnotesize{LCO}}
        (0,500) node[anchor=west, black] {\footnotesize{post-test}};

        %\addplot[black, solid, mark=none] table[header=false, x index={0}, y expr=\thisrowno{1}, skip first n={53}] {fresh.uxd};  % only necessary for the real plots
        %\addplot[black, solid, mark=none] table[header=false, x index={0}, y expr=\thisrowno{1}+3000, skip first n={53}] {pt.uxd}; % only necessary for the real plots

        % references: PDF files
        \addplot[ybar,bar width=0.01pt,green!60!black, fill=green!60!black, ybar legend] table[header=false, x index={0}, y expr=\thisrowno{1}*1.1, skip first n={1}] {01-080-0579_La2CuO4_PDF.dat};

        \addplot+[ycomb, solid, mark={}, mark options={purple}, purple] table[header=false, x index={0}, y expr=\thisrowno{1}*4, skip first n={1}] {00-048-1113_La2O2CO3_PDF.dat};  % , yshift=4000, only works in x direction...
        %\addplot[ybar, bar width=0.01pt, purple, fill=purple, ybar legend] table[header=false, x index={0}, y expr=\thisrowno{1}*5, skip first n={1}] {\PfadXRD 00-048-1113_La2O2CO3_PDF.dat}; % bar shift=300pt, only works in x direction...
        %\addlegendentry[purple]{\ch{La2O2CO3} \footnotesize{(\#48-1113)}}

                \end{axis}
            \end{tikzpicture}
        \label{fig:XRD_MWE}
    \end{figure}

\end{document}

Is there any way to achieve this that I have overlooked?

edit2: I took down the data files since Jake wholly answered the question and removed the corresponding inactive links from the thread.

Best Answer

You can shift the whole combs in the y direction by adding shift={(axis direction cs:0,4000)}:

\documentclass[]{article}

\usepackage{textcomp}
\usepackage{chemmacros}

% % % Plotting % % %
\usepackage{tikz}
\usepackage{pgfplots}
\usepackage{pgfplotstable}
\usetikzlibrary{plotmarks}
\pgfplotsset{compat=1.10}

\begin{document}

    \begin{figure}[htb]
        \centering
            \begin{tikzpicture}
                \begin{axis}[
                width = 14 cm,
                height = 6 cm,
                xlabel={2$\theta$ (\textdegree)},
                axis x line=bottom,
                ylabel={intensity (a.\,u.)},
                axis y line=left,
                tick align=outside,
                xmin=10,
                xmax=80,
                ymin=0,
                yticklabels= ,
                scaled ticks=false,
                ]                   
        % XRD
        \axispath\draw  (500,500) node[anchor=west, green!60!black] {\footnotesize{\ch{La2CuO4} (\#80-0579)}}
        (500,450) node[anchor=west, purple] {\footnotesize{\ch{La2O2CO3} (\#48-1113)}}
        (0,80) node[anchor=west, black] {\footnotesize{LCO}}
        (0,500) node[anchor=west, black] {\footnotesize{post-test}};
        \addplot[ycomb, green!60!black, ybar legend] table[header=false, x index=0, y expr=\thisrowno{1}*1.1, skip first n={1}] {01-080-0579_La2CuO4_PDF.dat};

        \addplot[ycomb, purple, shift={(axis direction cs:0,4000)}] table[header=false, x index=0, y index=1, skip first n={1}] {00-048-1113_La2O2CO3_PDF.dat};  % 

                \end{axis}
            \end{tikzpicture}
        \label{fig:XRD_MWE}
    \end{figure}

\end{document}
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