#211 polaraxis: inaccurate plots with coord trafo and 'data cs=rad'

[Qwer Tzuio]

Hi,

combining polaraxis with coordinate transformations and data in radian coordinate system leads to inaccurate axis markers and slightly rotated grid lines. A minimum example to reproduce and illustrate the issue is given here:

\documentclass[tikz]{standalone}
\usepackage{pgfplots}
\usepgfplotslibrary{polar}
\usetikzlibrary{calc}
\begin{document}
% using rad-system -> broken
\begin{tikzpicture}
  \begin{polaraxis}[
    xtick={0,90,180,270}, % works ok without
    x coord trafo/.code=\pgfmathparse{#1-pi/2}, % rotate by 90°
    x coord inv trafo/.code=\pgfmathparse{#1+90}, % rotate back
    ]
    \addplot[data cs=polarrad, ] coordinates {(pi/2,0.5) (0,0.5)};
  \end{polaraxis}
\end{tikzpicture}
% using deg-system -> ok
\begin{tikzpicture}
  \begin{polaraxis}[
    xtick={0,90,180,270}, 
    x coord trafo/.code=\pgfmathparse{#1-90}, % rotate by 90°
    x coord inv trafo/.code=\pgfmathparse{#1+90}, % rotate back
    ]
    \addplot[] coordinates {(90,0.5) (0,0.5)};
  \end{polaraxis}
\end{tikzpicture}
\end{document}

The code and the resulting PDF output are appended.

I would appreciate a fix for the issue, if possible. Please let me know if you need any further information.