[Tex/LaTex] Multiple plots with error bars

pgfplots

I want to plot two graphs with error bars from an external file. The data file contains the columns x, y1, y1+, y1-, y2, y2+, y2-, where y1+ etc. are the error bars for the corresponding y-values. Now I am somehow unable to tell Latex to which y (1 or 2) it should add the error bars. I end up with graph y1 having in total 4 error bars (y1+, y1-, y2+, y2-) and y2 having none.

This is the code that I tried:

\documentclass[article]{standalone}

 \usepackage{tikz}
 \usepackage{pgfplots}
 \pgfplotsset{compat = newest}  % loads newest improved settings

\begin{document}

\begin{tikzpicture}

\begin{axis}[scale only axis, xlabel = x, xmin = -1, xmax = 1, ylabel = y,  ymax = 1.3e19, ymin = 0, ytick pos=left]


\addplot[clip marker paths=true,color = blue,mark = none,thick,]
 table [y index = 1] {1bar_density_data.txt};

\addplot+[only marks, blue, mark=*, mark options={blue}, error bars/.cd,y dir=plus,  y explicit] table [y error index=2]{1bar_density_data.txt};
\addplot+[blue, only marks, mark=*, mark options={blue}, error bars/.cd,y dir=minus,  y explicit] table [y error index=3]{1bar_density_data.txt};


\addplot[clip marker paths=true, color = green, mark = none,]
 table [y index = 4] {1bar_density_data.txt};

\addplot+[only marks, green, mark=*, mark options={green}, error bars/.cd,y dir=plus,  y explicit] table [y error index=5]{1bar_density_data.txt};
\addplot+[green, only marks, mark=*, mark options={green}, error bars/.cd,y dir=minus,  y explicit] table [y error index=6]{1bar_density_data.txt};

 \end{axis}
 \end{tikzpicture}
 \end{document}

With this resultenter image description here

Thanks!

Best Answer

Your problem is that you have not specified which y value you want to plot with the error bars, so the default value of y index=1 is used for both plots, even though the error bars are properly specified. The following MWE gives me two sets of y data with two error bars each. Note that I have

  1. Removed \usepackage{tikz} because pgfplots already does this
  2. Removed the (unused?) article option to standalone
  3. Added explicit x index options to the clip marker paths plots
  4. Removed the + from the \addplot specification because you're setting most of the relevant options anyways
\documentclass{standalone}
\usepackage{pgfplots}
\pgfplotsset{
    compat=1.11, % loads newest improved settings
    width=9.5cm,
    height=5cm,
}
\begin{document}

\begin{tikzpicture}
\begin{axis}[
scale only axis,
xlabel = y-Position (mm),
xmin = -1,
xmax = 1,
ylabel = Normalized Electron Density (a.u.),
ymax = 1.0e19,
ymin = 0,
ytick pos=left
]
\addplot[clip marker paths=true,color = blue,mark = none,thick,] table [x index=0, y index=1] {1bar_density_data.txt};
\addplot[only marks, blue, mark=*, mark options={blue}, error bars/.cd,y dir=plus,  y explicit] table [x index=0, y index=1, y error index=2]{1bar_density_data.txt};
\addplot[blue, only marks, mark=*, mark options={blue}, error bars/.cd,y dir=minus,  y explicit] table [x index=0, y index=1, y error index=3]{1bar_density_data.txt};
\addplot[clip marker paths=true, color = green, mark = none,] table [x index=0, y index=4] {1bar_density_data.txt};
\addplot[only marks, green, mark=*, mark options={green}, error bars/.cd,y dir=plus,  y explicit] table [x index=0, y index=4, y error index=5]{1bar_density_data.txt};
\addplot[green, only marks, mark=*, mark options={green}, error bars/.cd,y dir=minus,  y explicit] table [x index=0, y index=4, y error index=6]{1bar_density_data.txt};
\end{axis}
\end{tikzpicture}
\end{document}

enter image description here

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