1 2##============================================================================== 3## getellipse : calculates the x-y values for (part of) an ellipse 4##============================================================================== 5 6getellipse <- function (rx=1, ry=rx, mid=c(0,0), dr=0.01, 7 angle=0, from=-pi, to=pi) { 8 9 dr <- abs(dr) 10 if (to < from) to <- 2*pi + to 11 x <- c( seq(from,to,by=dr), to) 12 if (x[length(x)] == x[length(x)-1]) 13 x <- x[-length(x)] 14 xy <- cbind( mid[1] + rx * cos(x), mid[2] + ry * sin(x)) 15 16 if (angle != 0) 17 xy <- rotatexy (xy, angle=angle, mid=mid) # rotate around mid 18 return(xy) 19} 20