[Tex/LaTex] Polar plots, add degree symbol and hide the radius axis labels

pgfplotssymbolstikz-pgf

I'm using sublime text 2 with skim, on Mac OSX 10.8.3.

I'm plotting microphone pick up patterns as follows:

    \begin{tikzpicture} % p56
    \begin{polaraxis} [ytick=\empty,legend entries={Omnidirectional,Figure-8,,Subcardioid,Cardioid,Supercardioid,,,,Hypercardioid,,,,},legend cell align=left,legend style={at={(1.7,0.5)},anchor=east}]
        %Ominidirectional
    \addplot[style=thick,domain=0:360, samples=100]{1};
        %Figure 8 (Bidirectional)
    \addplot[style=thick,color=blue,domain=0:180, samples=100]{cos(x)};
    \addplot[style=thick,color=blue,domain=180:360, samples=100]{-cos(x)};
        %subcardiod
    \addplot[style=thick,color=green,domain=0:360, samples=100]{0.7 + 0.3*cos(x)};
        %cardiod
    \addplot[style=thick,color=brown,domain=0:360, samples=100]{0.5 + 0.5*cos(x)};
        %Supercardioid
    \addplot[style=thick,color=red,domain=0:126, samples=100]{0.37 + 0.63*cos(x)};
    \addplot[style=thick,color=red,domain=126:234, samples=100]{-0.37 - 0.63*cos(x)};
    \addplot[style=thick,color=red,domain=234:360, samples=100]{0.37 + 0.63*cos(x)};
        %Hypercardioid
    \addplot[style=thick,color=violet, domain=0:110, samples=100]{0.25 + 0.75*cos(x)};
    \addplot[style=thick,color=violet,domain=110:250, samples=100]{-0.25 - 0.75*cos(x)};
    \addplot[style=thick,color=violet,domain=250:360, samples=100]{0.25 + 0.75*cos(x)};
    \end{polaraxis}
\end{tikzpicture}

This creates the correct polar plots, but the angles are without the degree symbol.

How can I add the degree symbol and also how can I remove the black radial line running from the centre horizontally to the right?

Best Answer

For printing the degree symbol in the tick labels, you can set xticklabel=$\pgfmathprintnumber{\tick}^\circ$ (\pgfmathprintnumber makes sure that the numbers are rounded nicely, \tick contains the label value, and \circ is the symbol).

The horizontal black line is the y axis, which you can hide using the key hide y axis.

Bonus hints: Instead of using empty legend entries, you can add forget plot to the helper plots. That way they won't get a legend entry. In your case, you don't even need the helper plots: You can let all plots run from 0 to 360 degrees, and use abs(<expr>) instead of just <expr> to get the same results.

For line plots, you don't need to say color=red, you can just say red.

Options that are common to all plots can be set using every axis plot/.style={thick, samples=100, domain=0:360}, which helps keep the code leaner and more maintainable.

\documentclass[border=5mm]{standalone}

\usepackage{pgfplots}
\usepgfplotslibrary{polar}
\begin{document}

 \begin{tikzpicture} % p56
    \begin{polaraxis} [
            ytick=\empty,
            hide y axis,
            xticklabel=$\pgfmathprintnumber{\tick}^\circ$,
            legend entries={
                Omnidirectional,
                Figure-8,
                Subcardioid,
                Cardioid,
                Supercardioid,
                Hypercardioid
            },
            legend cell align=left,
            legend style={
                at={(1.7,0.5)},
                anchor=east
            },
            every axis plot/.style={
                thick,
                samples=100,
                domain=0:360
            }
        ]
        %Ominidirectional
    \addplot[black]{1};
        %Figure 8 (Bidirectional)
    \addplot[blue]{abs(cos(x))};
        %subcardiod
    \addplot[green]{0.7 + 0.3*cos(x)};
        %cardiod
    \addplot[brown]{0.5 + 0.5*cos(x)};
        %Supercardioid
    \addplot[red]{abs(0.37 + 0.63*cos(x))};
        %Hypercardioid
    \addplot[violet]{abs(0.25 + 0.75*cos(x))};
    \end{polaraxis}
\end{tikzpicture}
\end{document}
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