Why is the root node not centered?

Question

I'm trying to code a star graph, using the tikz graphs library. This is what I have so far:

\documentclass[border=10pt]{standalone}

\usepackage{tikz} 
\usetikzlibrary{graphs}

\begin{document}
\pagestyle{empty}

\begin{tikzpicture}

    \graph [clockwise=10, radius=1cm] {
        hidden -> \foreach \i in {1,...,10} {p\i/$P_{\i}$}};

\end{tikzpicture}
\end{document}

The result is this:

Why is the root node not centered? Shouldn't everything be nicely disposed around (0, 0)?

Answer 1

If your plan is just to draw this particular circular graph, I would not use the graphs library but do the following:

\documentclass[border=3.14mm,tikz]{standalone}
\usetikzlibrary{shapes}

\begin{document}
    \begin{tikzpicture}
        \node[ellipse,inner sep=1pt] (h) {hidden};
        \foreach \i in {1,...,10}
            \draw [->] (h) -- (126-36*\i:2) node[shift=(123-36*\i:8pt)] (p\i){$P_{\i}$};
    \end{tikzpicture}
\end{document}

Note that I used a radius of 2cm, because with only 1 cm, all nodes were too close from the centre, for my taste.