# Let it snow!

December 14, 2012
By

(This article was first published on Probability and statistics blog » r, and kindly contributed to R-bloggers)

A couple days ago I noticed a fun piece of R code by Allan Roberts, which lets you create a digital snowflake by cutting out virtual triangles. Go give it a try. Roberts inspired me to create a whole night sky of snowflakes. I tried to make the snowfall look as organic as possible. There are lots of options to adjust. Here’s the code, have fun and Happy Holidays!

``` # Code by Matt Asher for statisticsblog.com # Feel free to modify and redistribute   # How many flakes do you want to fall? flakes = 100   # Width and height of your space width = 800 height = 600   # Initial wind wind = 0   # Setup the background of the plot and margins par(bg = "black") par(oma=c(0,0,0,0)) par(mar=c(0,0,0,0)) plot(0, 0, col="black", pch=".", xlim=c(0,width), ylim=c(0,height), axes=F)   for(i in 1:flakes) { startY = height startX = runif(1,1,width)   xPos = startX yPos = startY   for(j in 1:height) {   # Optional drift in wind wind = wind + rcauchy(1,0,.05)   # Update snowflake position xPos = xPos + rnorm(1,.1,1.5) yPos = yPos - runif(1,4,20)   # Are we in the space, if so display it if(xPos &gt; 0 &amp;&amp; xPos &lt;= width &amp;&amp; yPos &gt; 0 &amp;&amp; yPos &lt;= height) { points(round(xPos), round(yPos), col="white", pch=8)   # System dely, slows down the flakes Sys.sleep(0.1) } } } ```

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