generate heart plot for valentine's day

valetine.R

require(ggplot2)

t <- seq(0,2*pi, by=0.1)
x <- 16*sin(t)^3
y <- 13*cos(t) - 5*cos(2*t) - 2*cos(3*t) - cos(4*t)

d <- data.frame(x=x,y=y, f=0)

a <- x
b <- y
for (i in 1:30) {
    a <- a * 0.9
    b <- b * 0.9
    dd <- data.frame(x=a,y=b, f=i)
    d <- rbind(d, dd)
}


p <- ggplot(d, aes(x,y, group=factor(f))) +
    geom_path(aes(color="hotpink")) +
    opts(legend.position="none") +
    xlab("") + ylab("")



rotate <- function(mat, degree) {
    ## reference
    ## http://en.wikipedia.org/wiki/Rotation_matrix
    mat <- as.matrix(mat)
    theta <- degree/180 * pi
    r <- matrix(c(cos(theta), -sin(theta),
                  sin(theta), cos(theta)),
                byrow=T, ncol=2)
    mat <- (mat-colMeans(mat)) %*% r
    return(mat)
}


xy <- matrix(c(x,y), byrow=F, ncol=2)
xy2 <- rotate(xy, -30)
xy3 <- rotate(xy*0.7, 15)
d1 <- data.frame(x=xy2[,1], y=xy2[,2],f=1)
d2 <- data.frame(x=16+xy3[,1], y=xy3[,2]-3,f=2)
dfr <- rbind(d1,d2)

g <- ggplot(dfr, aes(x,y,
                     group=factor(f),
                     color=factor(f))) +
    geom_path() +
    geom_text(aes(x=13, y=10,
                  label="Happy Valentine's Day!",
                  colour="black",angle=-30)) +
    scale_color_manual(values=c("red",
                       "hotpink", "black")) +
    opts(legend.position="none") +
    xlab("") + ylab("")