How to put text above a node/point in tikz

Question

I'm very new to this site and just about as new to LaTeX. The question is simple: how do I get some text to appear above a node rather than inside of it? For example, I used this tikz stuff to make a cyclic graph:

\begin{figure}
\centering
\begin{tikzpicture}[scale=.7, every node/.style={circle,fill=blue!20}]
\node (n1) at (0,0) {1};
\node (n2) at (3,0) {2};
\node (n3) at (1.5,3) {3};
\draw (n1) -- (n2) -- (n3) -- (n1);
\end{tikzpicture}
\end{figure}

My attempts thus far have brought me to this:

\begin{figure}[h]
\centering
\begin{tikzpicture}
\filldraw [blue!20] (.5,0) circle (8pt);
\node (n1) at (.2,.5) {$x$};
\filldraw [blue!20] (3.5,0) circle (8pt);
\node (n2) at (3.75,.4) {$x-1$};
\filldraw [blue!20] (1.75,3) circle (8pt);
\node (n3) at (1.75,3.5) {$x-2$};
\draw (.5,0) -- (3.5,0) -- (1.75,3) -- (.5,0);
\end{tikzpicture}
\end{figure}

However, I don't like the use of \filldraw directive for the "nodes" as much as the \node directive. I copy/pasted from some website the stuff I started using tikz and so I'm not sure how to take the "globally applied" properties/settings and make them applicable to just a single node. I tried a few things, but this didn't help.

What I'm after is, basically, the effect of the second drawing. However, I'd like it to be better polished.

Thanks,
Andy

Answer 1

First, you can define styles for only specific nodes by

\begin{tikzpicture}[scale=.7,
    mycirc/.style={circle,fill=blue!20, minimum size=0.5cm}
    ]

and apply this style to a node by create it with

\node[mycirc] at (0,0) {};

Then, you can create labels for a node with

\node[mycirc, label={$x-1$}] at (0,0) {};

and you can define where this label is printed with

\node[mycirc, label=right:{$x-1$}] at (0,0) {};
\node[mycirc, label=left:{$x-1$}] at (0,0) {};
\node[mycirc, label=above:{$x-1$}] at (0,0) {};
\node[mycirc, label=below:{$x-1$}] at (0,0) {};

or even in any arbitrary angle with

\node[mycirc, label=165:{$x-1$}] at (0,0) {};

where 165 is the angle in degrees. 0 corresponds to right, 90 to above and so on.

So, with these changes, a minimal working example (MWE) of your graph looks like this:

\documentclass[tikz]{standalone}
\begin{document}
\begin{tikzpicture}[scale=.7,
    mycirc/.style={circle,fill=blue!20, minimum size=0.5cm}
    ]
    \node[mycirc,label=left:{$x$}] (n1) at (0,0) {};
    \node[mycirc,label=311:{$x-1$}] (n2) at (3,0) {};
    \node[mycirc,label=above:{$x-2$}] (n3) at (1.5,3) {};
    \draw (n1) -- (n2) -- (n3) -- (n1);

\end{tikzpicture}
\end{document}