recursive shape fractal generator

August 19, 2019
By

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Intro

This function allows us to generate the Sierpinski Triangle and explore other recursive shapes with equal length sides following the same algorithm.

shape <- function(corners, trials = 100000){
    
    corners <- as.integer(corners)
    points <- list()

    if (corners < 3) stop("Value should be 3 or greater")
 
    for (n in 1:(corners)){
     points$x[n] <- 0 + cos((2*pi*n)/corners)
        points$y[n] <- 0 + sin((2*pi*n)/corners)
    }

    x <- points$x[1]
    y <- points$y[1]

    trials <- trials
    sierpinski <- list()

    for (t in 1:trials){
        r <- sample(1:corners,1)
        x <- (x + points$x[r]) / sqrt(corners + 1)
        y <- (y + points$y[r]) / sqrt(corners + 1)
        sierpinski$x[t] <- x
        sierpinski$y[t] <- y
    }

 
    # I use these colors for random color selection. Update for your own desired selection.
    color <- sample(c("royalblue2", "firebrick2", "gold2", "springgreen3", "purple2", "darkorange1"),1)

    plot(sierpinski$x[corners:trials], sierpinski$y[corners:trials],
        xlab = paste0(corners, " Sides Chosen"), ylab = "", xaxt = "n", yaxt = "n", col = color)

}

When you run the function, you indicate the number of sides for the polygon and adjust the number of trials to change the resolution if desired. Here are some examples:

shape(3)

shape(4)

shape(6)

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