[R] r-ish ? how can i improve my code?

Sean O'Riordain seanpor at acm.org
Wed Oct 15 11:06:36 CEST 2003


Hi Folks,

I'm trying to learn R.  One of my intentions is to do some Monte-Carlo 
type modelling of road "accidents".

Below, to simplify things, I've appended a little program which does a 
'monte-carlo' type simulation.  However, it is written in a way which 
seems a bit un-natural in R.  Could someone help me make this a bit more 
R-ish please?

Or is there a completely different approach I should be taking?

Many thanks in advance,
Sean O'Riordain
seanpor AT acm.org


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n <- 900; # number of valid items required...

x <- numeric(n);
y <- numeric(n);
z <- numeric(n);

c <- 1;  # current 'array' pointer
tc <- 0; # total items actually looked at...

while (c <= n) {
     x[c] = runif(1, 0, 1);
     y[c] = runif(1, 0, 1);

     z[c] = sqrt(x[c]^2 + y[c]^2);
     if (z[c] < 1)
         c <- c + 1;
     tc <- tc + 1;
}

print("'overwork' ratio");
print(tc/(c-1));
plot(x,y);




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