in PGFPlots, use meta data for markers?

Question

Is there (I'm sure there must be) a way to use meta data for markers?

I have something like the below:

Year              coeff        meta
2005               1.2183       o
2006               0.1073       star
2007               0.5629       square
2008               1.0168       diamond
2009               -4.4083      otimes

And I'd like a scatter plot that uses meta data for the markers.

Thanks!

Answer 1

You can make the contents of the meta column available by adding point meta=explicit symbolic to the \addplot options, where the explicit indicates that the meta data is distinct from the y coordinate (by default, the y coordinate is used as the meta data), and the symbolic indicates that the values shouldn't be parsed as numbers.

Then you can use the scatter/@pre marker code to set the mark depending on the content of the meta variable:

\documentclass[border=5mm]{standalone}

\usepackage{pgfplots, pgfplotstable}

\begin{document}

\begin{tikzpicture}
\begin{axis}[/pgf/number format/1000 sep={}]
\addplot [
    point meta=explicit symbolic,
    scatter, only marks,
    scatter/@pre marker code/.code={\pgfplotsset{mark=\pgfplotspointmeta}},
    scatter/@post marker code/.code={}
] table [meta=meta] {
Year              coeff        meta
2005               1.2183       o
2006               0.1073       star
2007               0.5629       square
2008               1.0168       diamond
2009               -4.4083      otimes
};
\end{axis}
\end{tikzpicture}

\end{document}