Multiple pgfplots addplot commands in foreach loop

Question

I am trying to build upon the answer of Christian Feuersänger here: https://tex.stackexchange.com/a/17817/193625

Instead of just on \addplot I want to have multiple in the body of my loop. However this results in the error: Use of \pgffor@scanround doesn't match its definition.

Can anyone help?

MWE:

\documentclass{article}
\usepackage{pgfplots}
\pgfplotsset{compat=1.18}
\begin{document}
\begin{tikzpicture}
    \begin{axis}
        \foreach \x/\l in {-2/a, -1/b, 1/c, 2/d}{
            \edef\temp{\noexpand
                \addplot%
                    coordinates{ (\x, 0.5) (\x, 1) }
                    node [above] {\l};
                % comment the next three lines to make it work
                \addplot%
                    coordinates{ (\x, -0.5) (\x, -1) }
                    node [below] {\l};
            }
            \temp
        }
    \end{axis}
\end{tikzpicture}
\end{document}

You can place the second \addplot in another \edef\temp{\noexpand ... }\temp structure. — Jasper Habicht, Nov 30 '22 at 15:06

score 3 · Accepted Answer · answered Nov 30 '22 at 15:16

You need to place \noexpand before every \addplot macro:

\documentclass{article}
\usepackage{pgfplots}
\pgfplotsset{compat=1.18}
\begin{document}
\begin{tikzpicture}
    \begin{axis}
        \foreach \x/\l in {-2/a, -1/b, 1/c, 2/d}{
            \edef\temp{
                \noexpand\addplot%
                    coordinates{ (\x, 0.5) (\x, 1) }
                    node [above] {\l};
                \noexpand\addplot%
                    coordinates{ (\x, -0.5) (\x, -1) }
                    node [below] {\l};
            }
            \temp
        }
    \end{axis}
\end{tikzpicture}
\end{document}

You can also nest \foreach loops (this may further simplify things, depending on your concrete set up):

\documentclass{article}
\usepackage{pgfplots}
\pgfplotsset{compat=1.18}
\begin{document}
    \begin{tikzpicture}
        \begin{axis}
            \foreach \x/\l in {-2/a, -1/b, 1/c, 2/d}{
                \foreach \p/\ya/\yb in {above/0.5/1, below/-0.5/-1}{
                    \edef\temp{
                        \noexpand\addplot%
                            coordinates{ (\x, \ya) (\x, \yb) }
                            node [\p] {\l};
                    }\temp
                }
            }
        \end{axis}
    \end{tikzpicture}
\end{document}

Both yield:

Ty. So simple. It is just that I never really understand how latex works and I cannot make sense of most error messages. — Franz, Nov 30 '22 at 19:04

Multiple pgfplots addplot commands in foreach loop

1 Answers1