Fractal Fern

[This article was first published on Frank Portman, and kindly contributed to R-bloggers]. (You can report issue about the content on this page here)
Want to share your content on R-bloggers? click here if you have a blog, or here if you don't.

I’m gonna share a short code snippet that I thought was interesting. This post is inspired by one of my engineering computation classes at Rice. The program initializes a pair of coordinates ‘z’ and iteratively updates z by matrix multiplication based on some random number generation criteria. After each successive coordinate update, the new ‘z’ is plotted.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
library(ggplot2)

z <- matrix(c(0, 0), nrow = 2)
x <- c()
y <- c()

for (i in 1:40000) {

  r <- runif(1)

  if (r < .01) {
    z <- matrix(c(0, 0, 0, .16), nrow = 2, byrow = T) %*% z
  }

  else if (r < .86) {
    z <- matrix(c(.85, .04, -.04, .85), nrow = 2, byrow = T) %*% z + c(0, 1.6)
  }

  else if (r < .93) {
    z <- matrix(c(0.2, -.26, .23, .22), nrow = 2, byrow = T) %*% z + c(0, 1.6)
  }

  else {
    z <- matrix(c(-.15, .28, .26, .24), nrow = 2, byrow = T) %*% z + c(0, .44)
  }

  x[i] <- z[1]
  y[i] <- z[2]

}

qplot(x, y, size = I(.5)) + theme_bw() + opts(axis.line = element_blank(),
      axis.text.x = element_blank(), axis.text.y = element_blank(),
      axis.ticks = element_blank(), axis.title.x = element_blank(),
      axis.title.y = element_blank()) + scale_x_continuous(breaks = NULL) +
      scale_y_continuous(breaks = NULL) + ggtitle("Fractal Fern")
	

Pretty.

To leave a comment for the author, please follow the link and comment on their blog: Frank Portman.

R-bloggers.com offers daily e-mail updates about R news and tutorials about learning R and many other topics. Click here if you're looking to post or find an R/data-science job.
Want to share your content on R-bloggers? click here if you have a blog, or here if you don't.

Never miss an update!
Subscribe to R-bloggers to receive
e-mails with the latest R posts.
(You will not see this message again.)

Click here to close (This popup will not appear again)