Direction arrows on a circle [duplicate]

Question

I would like to plot circle (or another curve) with positive direction (and show it wit arrows).

This plots the circle

\documentclass{article}
\usepackage{tikz}
\RequirePackage{pgfplots}
\usetikzlibrary{shadows}
\usetikzlibrary{shapes}
\usetikzlibrary{decorations}
\usepackage{verbatim}
\usepackage[active,tightpage]{preview}
\PreviewEnvironment{tikzpicture}
\setlength\PreviewBorder{5pt}
\begin{document}
\begin{tikzpicture}
    \begin{axis}[
            xmin=-1.5,xmax=2.5,ymin=-1.5,ymax=1.5,
            axis lines=center,
            ticks=none,
            unit vector ratio*=1 1 1,
           ]        
          \addplot [very thick, smooth, domain=(0:2*pi)] ({1.+cos(deg(x))},{sin(deg(x))});

      \addplot[only marks,mark=*] coordinates{(1,0)};
        \end{axis}
\end{tikzpicture}
\end{document}

And I want to add arrows like that

Would you advise me how to add such arrows?

Answer 1

This is your code with the addition of arrows and decorations.markings tikzlibraries plus a tikz style (redarrows.tikstyle) where the arrow heads are defined. The code lets you easily customize the color and the shape af the arrowheads. I used >, but if you like another style refer to the list contained in Is it possible to change the size of an arrowhead in TikZ/PGF? and just change the argument of \arrow inside the tikz style

\documentclass{article}

\usepackage{tikz}
\RequirePackage{pgfplots}
\usetikzlibrary{shadows}
\usetikzlibrary{shapes}
\usetikzlibrary{decorations}
\usetikzlibrary{arrows,decorations.markings}         %new code

\usepackage{verbatim}
\usepackage[active,tightpage]{preview}
\PreviewEnvironment{tikzpicture}

\setlength\PreviewBorder{5pt}

\begin{document}   
\tikzset{               %new code
    redarrows/.style={postaction={decorate},decoration={markings,mark=at position 0.1 with {\arrow[draw=red]{>}}},
           decoration={markings,mark=at position -0.4 with {\arrow[draw=red]{>}}},}}
\begin{tikzpicture}
    \begin{axis}[
            xmin=-1.5,xmax=2.5,ymin=-1.5,ymax=1.5,
            axis lines=center,
            ticks=none,
            unit vector ratio*=1 1 1,
           ]        
          \addplot [very thick, smooth, domain=(0:2*pi),redarrows] ({1.+cos(deg(x))},{sin(deg(x))});         %new code

      \addplot[only marks,mark=*] coordinates{(1,0)};
        \end{axis}
\end{tikzpicture}

\end{document}

Answer 2

With PSTricks.

\documentclass[pstricks,border=12pt]{standalone}
\usepackage{pst-plot}
\begin{document}
\begin{pspicture}(-1,-3)(5,3)
    \psaxes[labels=none,ticks=none,linecolor=gray](0,0)(-1,-3)(5,3)
    \pscircle[dimen=middle](2.5,0){2}
    \psset{arrows=->,arrowinset=0,arcsep=-1.5\pslinewidth,linecolor=red}
    \psarc(2.5,0){2}{44}{46}
    \psarc(2.5,0){2}{-136}{-134}
\end{pspicture}
\end{document}

Warning:

I don't know how to change the arrow head color more elegantly.