title: How fill part of a circle using ggplot2
body: <pre><code>circleFun &lt;- function(center = c(0,0),diameter = 1, npoints = 100){
  r = diameter / 2
  tt &lt;- seq(0,2*pi,length.out = npoints)
  xx &lt;- center[1] + r * cos(tt)
  yy &lt;- center[2] + r * sin(tt)
  return(data.frame(x = xx, y = yy))
  }
  dat &lt;- circleFun(c(1,-1),2.3,npoints = 100)
  ggplot(dat,aes(x,y)) + geom_path(color="black") + ggtitle("circle")
  </code></pre>
  
  <p>I am plotting with ggplot2. I want to fill the circle with blue only in first quadrant. What should I do?</p>
  
  <p>Thank you !</p>