R help - May 2012 - Numerical integration of a two dimensional function over a disk

Hello, there!
 
Basically my problem is very clear. I would like to take a
(numerical) integration of a function f(x,y) which can be quite complex of x and
y, over a disk (x-a)^2+(y-b)^2<= r^2 (with r constant). However, after some
search in R, I just cannot find a function in R that suits my purpose. Function
Integrate applies to one dimensional, and adaptIntegrate to rectangle. In my
case, it is not easy or simply impossible to transform the definition area to a
rectangle with constant boundaries.   I must have missed something, but is there
any R function which can solve the integration without going to ex. Monto Carlo?
Many thanks in advance!
 
Best regards,
Yingfu
	[[alternative HTML version deleted]]

"Simply impossible" seems an odd description for a technique described
in every elementary calculus text under the heading "integration in
cylindrical coordinates".
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yingfu xie <xieyingfu at yahoo.com> wrote:
>Hello, there!
>?
>Basically my problem is very clear. I would like to take a
>(numerical)?integration of a function f(x,y) which can be quite complex
>of x and y, over a disk (x-a)^2+(y-b)^2<= r^2 (with r constant).
>However, after some search in R, I just cannot find a function in R
>that suits my purpose. Function Integrate applies to one dimensional,
>and adaptIntegrate to?rectangle. In my case, it is not easy or
>simply?impossible?to transform?the definition area?to a rectangle with
>constant?boundaries. ??I must have missed something, but is there any R
>function which can solve the integration without going to ex. Monto
>Carlo? Many thanks in advance!
>?
>Best regards,
>Yingfu
>	[[alternative HTML version deleted]]
>
>______________________________________________
>R-help at r-project.org mailing list
>https://stat.ethz.ch/mailman/listinfo/r-help
>PLEASE do read the posting guide
>http://www.R-project.org/posting-guide.html
>and provide commented, minimal, self-contained, reproducible code.

...still new to R and trying to figure this one out.

I have a number of variables x, y, z, etc. in a data frame.

Each contains a 2 digit year (e.g., 80, 81, 82) representing the 
first year that something occurred. Each variable represents a 
different type of event.

If the event did not occur at all, the variable has the value 0 (zero).

I need to create a new variable having the value of the earliest year 
among the set of variables.

If none of the events occurred (all variables = 0), then the new 
variable should also be zero.

e.g.,

Original
x    y   z
80 82 83
85  76  90
90  0   86
0   0   0


New variable
80
76
86
0

On Tue, May 08, 2012 at 02:50:47PM -0500, Jeff wrote:
> 
> ...still new to R and trying to figure this one out.
> 
> I have a number of variables x, y, z, etc. in a data frame.
> 
> Each contains a 2 digit year (e.g., 80, 81, 82) representing the 
> first year that something occurred. Each variable represents a 
> different type of event.
> 
> If the event did not occur at all, the variable has the value 0 (zero).
> 
> I need to create a new variable having the value of the earliest year 
> among the set of variables.
> 
> If none of the events occurred (all variables = 0), then the new 
> variable should also be zero.
> 
> e.g.,
> 
> Original
> x    y   z
> 80 82 83
> 85  76  90
> 90  0   86
> 0   0   0
> 
> 
> New variable
> 80
> 76
> 86
> 0
Hi.

If all years are at most 99, then try the following

  dat <- data.frame(x=c(80, 85, 90, 0), y=c(82, 76, 0, 0), z=c(83, 90, 86,
0))
  dat[dat == 0] <- Inf
  out <- pmin(dat$x, dat$y, dat$z)
  out[out == Inf] <- 0
  out

  [1] 80 76 86  0

Hope this helps.

Petr Savicky.