From 1e9baf6e684d2f4f29eaa9fe1f506ed1233904b7 Mon Sep 17 00:00:00 2001
From: Xu Yuan <xu@informatik.hu-berlin.de>
Date: Sat, 1 Oct 2011 22:30:00 +0200
Subject: polar pie!

---
 dev/demo/population.tex |  6 +++---
 dev/pgf-pie-manual.tex  |  7 +++++++
 dev/pgf-pie.sty         | 39 ++++++++++++++++++++++++++++++++++++---
 3 files changed, 46 insertions(+), 6 deletions(-)

diff --git a/dev/demo/population.tex b/dev/demo/population.tex
index d64b8b8..1b39664 100644
--- a/dev/demo/population.tex
+++ b/dev/demo/population.tex
@@ -1,6 +1,6 @@
 % data from http://en.wikipedia.org/wiki/List_of_countries_by_population
 \begin{tikzpicture}
-  \pie[sum=auto, radius=35, after number=, text=pin] {1339/China,
+  \pie[polar, sum=auto, radius=35, after number=, text=pin] {1339/China,
     1210/India, 312/USA, 237/Indonesia, 190/Brazil, 177/Pakistan,
     158/Nigeria, 151/Bangladesh, 142/Russia, 127/Japan, 112/Mexico,
     94/Philippines, 87/Vietnam, 82/Ethiopia, 81/Germany, 80/Egypt,
@@ -22,6 +22,6 @@
     Emirates, 8/South Sudan, 8/Honduras, 8/Switzerland, 8/Israel,
     7/Bulgaria, 7/Serbia, 7/Hong Kong }
 
-  \node[circle,draw=black,thick, fill=white, font=\LARGE\bf]
-  {Population of the world};
+  % \node[circle,draw=black,thick, fill=white, font=\bf]
+  % {Population of the world};
 \end{tikzpicture}
diff --git a/dev/pgf-pie-manual.tex b/dev/pgf-pie-manual.tex
index b8acc99..6eb7809 100644
--- a/dev/pgf-pie-manual.tex
+++ b/dev/pgf-pie-manual.tex
@@ -90,6 +90,13 @@ keywordstyle=\color{blue}
 \subsection{First Pie}
 \demo[0.6]{first-pie}
 
+\subsection{Polar area diagram}
+The polar area diagram is similar to a usual pie chart, except sectors
+are equal angles and differ rather in how far each sector extends from
+the center of the circle.
+
+\demo[0.6]{polar}
+
 \subsection{Position, Rotation, Size}
 
 The center of chart can be set by \texttt{pos}, default is
diff --git a/dev/pgf-pie.sty b/dev/pgf-pie.sty
index 0fa3b26..84cbb1c 100644
--- a/dev/pgf-pie.sty
+++ b/dev/pgf-pie.sty
@@ -50,6 +50,7 @@ chart by using PGF/Tikz package.]
 \newcounter{pgfpie@angleEnd}
 \newcounter{pgfpie@explodeLength}
 \newcounter{pgfpie@colorLength}
+\newcounter{pgfpie@sliceLength}
 
 \def\setexplode#1\pgfeov{\def\explode{#1}}
 \pgfkeyslet{/explode/.@cmd}{\setexplode}
@@ -81,8 +82,12 @@ chart by using PGF/Tikz package.]
 \def\setrotate#1\pgfeov{\xdef\rotate{#1}}
 \pgfkeyslet{/rotate/.@cmd}{\setrotate}
 
+\newif\ifpolar
+\pgfkeys{/polar/.is if=polar}
+
 \newcommand{\pie}[2][]
 {
+  % load default parameters
   \pgfkeys{
     explode=0,
     color={blue!60, cyan!60, yellow!60, orange!60, red!60,
@@ -96,9 +101,12 @@ chart by using PGF/Tikz package.]
     text=label,
     sum=100,
     rotate=0,
+    polar=false,
   }
+  % load user's parameters
   \pgfkeys{#1}
 
+  % handle sum
   \ifthenelse{\equal{\sum}{auto}}
   {
     % sum all input
@@ -111,7 +119,7 @@ chart by using PGF/Tikz package.]
   }
   {}
 
-
+  % init counters
   \setcounter{pgfpie@explodeLength}{0}
   \foreach \e in \explode { \addtocounter{pgfpie@explodeLength}{1} }
 
@@ -120,10 +128,35 @@ chart by using PGF/Tikz package.]
   
   \setcounter{pgfpie@angleEnd}{0}
 
+  \ifpolar
+    \setcounter{pgfpie@sliceLength}{0}
+    \xdef\maxValue{0}
+    \foreach \p/\e in {#2} {
+      \addtocounter{pgfpie@sliceLength}{1}
+      \ifnum \maxValue < \p
+        \xdef\maxValue{\p}
+      \fi
+    }
+    \pgfmathparse{\sum / \value{pgfpie@sliceLength}}
+    \xdef\polarangle{\pgfmathresult}
+    \pgfmathparse{\radius / \maxValue}
+    \xdef\polarRadiusUnit{\pgfmathresult}
+  \else
+    \xdef\theradius{\radius}
+  \fi
+
+  % drawing loop
   \foreach \p/\t [count=\i from 0] in {#2}
   {
     \setcounter{pgfpie@angleBegin}{\value{pgfpie@angleEnd}}
-    \addtocounter{pgfpie@angleEnd}{\p}
+    \ifpolar
+      % Polar area diagram
+      \addtocounter{pgfpie@angleEnd}{\polarangle}
+      \xdef\theradius{\p*\polarRadiusUnit}
+    \else
+      % normal pie
+      \addtocounter{pgfpie@angleEnd}{\p}
+    \fi
 
     % find explode
     \pgfmathparse{int(mod(\i,\value{pgfpie@explodeLength}))}
@@ -151,7 +184,7 @@ chart by using PGF/Tikz package.]
     {\t}
     {\theexplode}
     {\thecolor}
-    {\radius}
+    {\theradius}
     {\pos}
     {\style}
   }
-- 
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