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

[Spencer Graves]

      1.  I suggest you avoid using "c" as a loop index, as it conflicts 
with the name of a function.  R is smart enough to figure out the 
difference in some cases but not in all. 

      2. How about the following: 

n <- 900
x <- runif(n)
y <- runif(n)
z <- sqrt(x^2+y^2)
print(list(Overwork.ratio = n/sum(z<1)))
plot(x, y)
theta <- seq(0, pi/2, length=31)
lines(sin(theta), cos(theta))
######################

      This won't give you n numbers z < 1.  If you need exactly that, 
what about first generating, say, 2*n, then either throwing away the 
excess or generating another 2*n if you don't have enough?  You can use 
a recursive function for this, which would almost never recurse with 2*n 
but might with 1.1*n. 

      hope this helps.  spencer graves

Sean O'Riordain wrote:

> 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
>
>
> --------------------------------------------
> 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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