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April 2, 2016 09:15
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R code to generate a random christmas tree
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# This appeared on R-blogger, a post by "wingfeet" from 23 December 2013: http://www.r-bloggers.com/merry-christmas-2/ | |
# I stumbled acroos it and didn't want to lose it so I placed it here | |
part <- list(x0=0,y0=0,x1=0,y1=1, | |
branch1=NULL,branch2=NULL,extend=NULL, | |
lwd=1,depth=0,col='springgreen') | |
par(mfrow=c(1,1),mar=c(5, 4, 4, 2) + 0.1) | |
segplot <- function(tree) { | |
if (is.null(tree)) return() | |
segments(tree$x0,tree$y0,tree$x1,tree$y1, | |
col=tree$col, | |
lwd=tree$lwd) | |
segplot(tree$branch1) | |
segplot(tree$branch2) | |
segplot(tree$extend) | |
} | |
#segplot(part) | |
grow <- function(tree) { | |
if (is.null(tree) ) return(NULL) | |
tree$lwd=tree$lwd*1.2 | |
if (tree$lwd>2.5) tree$col <- 'brown' | |
if (is.null(tree$extend)) { | |
tree$extend <- list( | |
x0=tree$x1, | |
y0=tree$y1, | |
x1=rnorm(1,1,.03)*(2*tree$x1-tree$x0), | |
y1=(rnorm(1,.98,.02)+.02*(tree$x1==tree$x0))*(2*tree$y1-tree$y0), | |
branch1=NULL, | |
branch2=NULL, | |
extend=NULL, | |
lwd=1, | |
depth=tree$depth, | |
col=tree$col | |
) | |
length=sqrt((tree$x1-tree$x0)^2 + (tree$y1-tree$y0)^2) | |
angle <- asin((tree$x1-tree$x0)/length) | |
branch <- list( | |
x0=(tree$x1+tree$x0)/2, | |
y0=(tree$y1+tree$y0)/2, | |
branch1=NULL, | |
branch2=NULL, | |
extend=NULL, | |
lwd=1, | |
depth=tree$depth, | |
col=tree$col | |
) | |
shift <- rnorm(2,.5,.1) | |
branch$x0 <- shift[1]*tree$x1+(1-shift[1])*tree$x0 | |
branch$y0 <- shift[1]*tree$y1+(1-shift[1])*tree$y0 | |
length=length*rnorm(1,.5,.05) | |
co <- runif(1,.35,.45) | |
branch$x1 <- branch$x0+sin(angle+co)*length | |
branch$y1 <- branch$y0+cos(angle+co)*length | |
tree$branch1 <- branch | |
branch$x0 <- shift[2]*tree$x1+(1-shift[2])*tree$x0 | |
branch$y0 <- shift[2]*tree$y1+(1-shift[2])*tree$y0 | |
co <- runif(1,.35,.45) | |
branch$x1 <- branch$x0+sin(angle-co)*length | |
branch$y1 <- branch$y0+cos(angle-co)*length | |
tree$branch2 <- branch | |
} else { | |
tree$branch1 <- grow(tree$branch1) | |
tree$branch2 <- grow(tree$branch2) | |
tree$extend <- grow(tree$extend) | |
} | |
tree$depth <- tree$depth+1 | |
if (tree$depth>2) tree$col <- 'green' | |
if (tree$depth>4) tree$col <- 'darkgreen' | |
if (tree$depth>6) tree$col <- 'brown' | |
tree | |
} | |
tree <- part | |
for (i in 1:9) tree <- grow(tree) | |
par(mar=c(0,0,0,0)) | |
plot(x=c(-3,3),y=c(0,9),type='n',axes=FALSE,xlab='',ylab='') | |
segplot(tree) |
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