documentclass{article}

usepackage{tikz}
usepackage{pgf-pie}

begin{document}

begin{tabular}{|p{4cm}|p{4cm}|p{4cm}|}

$frac{1}{2}$ & $frac{2}{2}$ \

% 1/2
begin{tikzpicture}

pie[rotate=90, radius=2, sum=auto, color={white,blue}, /tikz/nodes={opacity=0,overlay}] {1 , 1 }

end{tikzpicture}

&

% 2/2
begin{tikzpicture}

pie[rotate=90, radius=2, sum=auto, color={blue,blue}, /tikz/nodes={opacity=0,overlay}] {1 , 1 }

end{tikzpicture}

\

$frac{1}{3}$ & $frac{2}{3}$ & $frac{3}{3}$ \


% 1/3
begin{tikzpicture}

pie[rotate=90, radius=2, sum=auto, color={white,white,blue}, /tikz/nodes={opacity=0,overlay}] {1 , 1, 1 }

end{tikzpicture}

&

% 2/3
begin{tikzpicture}

pie[rotate=90, radius=2, sum=auto, color={white,blue,blue}, /tikz/nodes={opacity=0,overlay}] {1 , 1, 1 }

end{tikzpicture}

&

% 3/3
begin{tikzpicture}

pie[rotate=90, radius=2, sum=auto, color={blue,blue,blue}, /tikz/nodes={opacity=0,overlay}] {1 , 1, 1 }

end{tikzpicture}


end{tabular}

end{document}

newcommand{rationalpie}[2]{
    begin{tikzpicture}

    pie[rotate=90, radius=2, sum=auto, color={white,blue,blue}, /tikz/nodes={opacity=0,overlay}] {1 , 1, 1 }

    end{tikzpicture}
}

rationalpie{2}{3}

documentclass{article}
usepackage{pgf-pie}
usepackage{forloop}
newtokscolors
newtoksparts
newcounter{parts}
newcommandrationalpiex[2]%
  {begin{tikzpicture}
   pie[rotate=90, radius=2, sum=auto, color={#1}, /tikz/nodes={opacity=0,overlay}] {#2}
   end{tikzpicture}%
  }
newcommandrationalpie[2]%
  {colors{}parts{}%
   forloop[-1]{parts}{#2}{value{parts} > 0}%
     {partsexpandafter{theparts1}%
      ifthenelse{value{parts} > #1}%
        {colorsexpandafter{thecolors white}}%
        {colorsexpandafter{thecolors blue}}%
      ifthenelse{value{parts} > 1}%
        {partsexpandafter{theparts,}%
         colorsexpandafter{thecolors,}%
        }%
        {}%
     }%
   edefrationalpiexx{noexpandrationalpiex{thecolors}{theparts}}%
   rationalpiexx
  }

begin{document}
begin{tabular}{|p{4cm}|p{4cm}|p{4cm}|}
$frac12$      & $frac22$                      \
rationalpie12 & rationalpie22                 \
$frac13$      & $frac23$      & $frac33$     \
rationalpie13 & rationalpie23 & rationalpie33
end{tabular}
end{document}