Using \addplot+ and \foreach in pgfplot

Question

I have four text files with each 21 columns, and I want to plot, for each file, the first column as x, and then the 20 next columns as y. For each file, then put it all together on the same graph. It's basically 20 replicates under 4 different conditions.

I have the following code, using \foreach, but I'd like to make it cleaner by using \addplot+ rather than \addplot with the fill argument. If I use \addplot+ within the \foreach loop, then each replicate has it's own color, and it's not really what I want.

To be clear, the following code does what I want, but I'd like to hear about solutions to make it nicer.

\documentclass[professionalfonts,11pt]{beamer}
\begin{document}
\begin{frame}{Conséquences des variations du taux de croissance}

\begin{center}
    \begin{tikzpicture}
        \begin{semilogyaxis}[
            xlabel=Temps,
            ylabel={Taille de population},
            cycle list name = monokai,
            legend pos = north west
            ]
            \foreach \yindex in {2,...,20}
                \addplot[mark = none, draw = RYB1] table [y index = \yindex] {data/vardem_30.dat};
            \foreach \yindex in {2,...,20}
                \addplot[mark = none, draw = RYB2] table [y index = \yindex] {data/vardem_10.dat};
            \foreach \yindex in {2,...,20}
                \addplot[mark = none, draw = RYB3] table [y index = \yindex] {data/vardem_3.dat};
            \foreach \yindex in {2,...,20}
                \addplot[mark = none, draw = RYB4] table [y index = \yindex] {data/vardem_1.dat};
        \end{semilogyaxis}
    \end{tikzpicture}
\end{center}

\end{frame}
\end{document}

Answer 1

• Your example is missing \usepackage{pgfplots}
• You don't neccessarily need draw=color, just color is enough
• As percusse said, one foreach loop should be enough
• You said you had 21 colums, so the loop should run to that value
• \addplot[options] should only execute the options, so you can leave out the mark=none. Otherwise you may specify \pgfplotsset{every axis plot post/.append style={mark=none}}

---

\documentclass[professionalfonts,11pt]{beamer}
\usepackage{pgfplots}

\begin{document}

\begin{frame}{Conséquences des variations du taux de croissance}
    \begin{center}
        \begin{tikzpicture}
          \begin{semilogyaxis}
          [ xlabel=Temps,
            ylabel={Taille de population},
            cycle list name = monokai,
            legend pos = north west,
            ]
          \foreach \yindex in {2,...,21}
            {   \addplot[RYB1] table [y index = \yindex] {data/vardem_30.dat};
            \addplot[RYB2] table [y index = \yindex] {data/vardem_10.dat};
            \addplot[RYB3] table [y index = \yindex] {data/vardem_3.dat};
            \addplot[RYB4] table [y index = \yindex] {data/vardem_1.dat};
            } 
          \end{semilogyaxis}
        \end{tikzpicture}
    \end{center}
\end{frame}

\end{document}