# David Kauchak
# 11/20/2011
#
# Some example R functions

# 1
mystery1 <- function(num){
	count <- 0
	current <- 1
	
	while(count < num){
		if( mystery2(current) ){
			print(current)
			count <- count + 1
		}
		
		current <- current + 1
	}
}

# 2
# though this does have a small bug in it...
mystery2 <- function(num){
	for( i in 2:sqrt(num) ){
		if( num %% i == 0 ){
			return(FALSE)
		}
	}
	
	return(TRUE)
}

# 3
mystery3 <- function(num){
	in_circle <- 0
	
	for( i in 1:num){
		x <- runif(1, 0, 1)
		y <- runif(1, 0, 1)
		
		dist <- sqrt(x^2 + y^2)
		
		if( dist < 1 ){
			in_circle <- in_circle + 1
		}
	}
	
	return(4 * in_circle/num)
}

# same thing, but a bit faster
mystery3b <- function(num){
	x <- runif(num, 0, 1)
	y <- runif(num, 0, 1)
	distances <- sqrt(x^2 + y^2)
	return(4 * sum(distances < 1)/num)
}


# 4
# assume the data in the file is numbers
mystery4 <- function(file){
	data <- scan(file)
	
	print(paste("Average:", mean(data)))
	print(paste("Max:", max(data)))
	print(paste("Non-zero:", sum(data != 0)))	
}