#61 [pos] add key that allows to snap to nearest (given) coordinate also when there is a line present

[Stefan Pinnow]

I am requesting two features here:

1. add a key that imitates the "snap to nearest" feature for pos also for \addplots showing lines
2. add a key that allows stating the "\coordindex" to place a node on that position.

Here is a third one from the PGFPlotsToDo list (which I moved here. I guess, also this request was from me ;)).

1. Implement something like pos={x=40}.

And here another point from PGFPlotsToDo which is related (and I moved here).

modify the node[at=<pos>] feature such that
node[at value=42.4] or at max value or at min value or
node[at coordindex=3]

---

\documentclass[border=5pt]{standalone}
\usepackage{pgfplots}
\begin{document}
    \begin{tikzpicture}
        \begin{axis}[
            domain=0:360,
        ]
            \addplot {sin(x)}
                    [yshift=8pt]
                % provide a key that allows to have the same positions as
                % given for the next `\addplot';
                % e.g. that imitates the "snap to nearest" feature for plots
                % with `only marks' active.
                %
                % In addition it would be nice to state just the coordinate
                % index to put a node to that one
                % (e.g. it could be named `pos index' or something like that)
                node [pos=0.0] {$a$}
                node [pos=0.2] {$b$}
                node [pos=0.4] {$c$}
                node [pos=0.6] {$d$}
                node [pos=0.8] {$e$}
            ;
            \addplot+ [only marks] {sin(x)}
                    [yshift=8pt]
                node [pos=0.0] {$a$}
                node [pos=0.2] {$b$}
                node [pos=0.4] {$c$}
                node [pos=0.6] {$d$}
                node [pos=0.8] {$e$}
            ;
        \end{axis}
    \end{tikzpicture}
\end{document}

---

And this should be fixed as well when implementing this feature (moved here from PGFPlotsToDo):

Das pos= feature funktioniert nur ungenau für smooth. Implementiere es genauer.