R help - Jun 2006 - looking for a more efficient R code.

Dear R-users

I have four simple linear models, which are all in the form of a*X+b
The estimated parameter vectors are

a <- c(1,2,3,4)
b <- c(4,3,2,1)

My goal is to draw a plot where x-axis is X (range from -100 to 100) and 
y-axis is the sum of
all four linear models

X <- seq(-100,100, length=10000)
plot(X, sum of the four linear functions)

I started with a function for summing

summing <- function(a,b)
{temp <-0;
for (i in 1:length(a))
temp <- temp + a[i]*X+b[i]
}

plot(X, summing(a,b))

I am a R beginner.  I am looking for a more efficient R code.

Any help or advice will be appreciated.

Taka,

> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch [mailto:r-help-bounces at
stat.math.ethz.ch]
> On Behalf Of Taka Matzmoto
> Sent: Monday, June 26, 2006 5:21 PM
> To: r-help at stat.math.ethz.ch
> Subject: [R] looking for a more efficient R code.
> 
> Dear R-users
> 
> I have four simple linear models, which are all in the form of a*X+b
> The estimated parameter vectors are
> 
> a <- c(1,2,3,4)
> b <- c(4,3,2,1)
> 
> My goal is to draw a plot where x-axis is X (range from -100 to 100) and
> y-axis is the sum of
> all four linear models
> 
> X <- seq(-100,100, length=10000)
> plot(X, sum of the four linear functions)
> 
> I started with a function for summing
> 
> summing <- function(a,b)
> {temp <-0;
> for (i in 1:length(a))
> temp <- temp + a[i]*X+b[i]
> }
> 
> plot(X, summing(a,b))
> 
> I am a R beginner.  I am looking for a more efficient R code.
> 
> Any help or advice will be appreciated.
> 
> Taka,
> 
Taka,

I won't claim more efficient, that is for you to decide.  But you might try
something like:

plot(x, colSums(t(x %*% t(b)) + a))

Dan

Daniel Nordlund
Bothell, WA

try this:

a <- c(1,2,3,4)
b <- c(4,3,2,1)
X <- seq(-100,100, length=10000)
z <- colSums(sapply(X,function(x)a*x+b))
plot(X, z, type='l')


On 6/26/06, Taka Matzmoto <sell_mirage_ne@hotmail.com>
wrote:
>
> Dear R-users
>
> I have four simple linear models, which are all in the form of a*X+b
> The estimated parameter vectors are
>
> a <- c(1,2,3,4)
> b <- c(4,3,2,1)
>
> My goal is to draw a plot where x-axis is X (range from -100 to 100) and
> y-axis is the sum of
> all four linear models
>
> X <- seq(-100,100, length=10000)
> plot(X, sum of the four linear functions)
>
> I started with a function for summing
>
> summing <- function(a,b)
> {temp <-0;
> for (i in 1:length(a))
> temp <- temp + a[i]*X+b[i]
> }
>
> plot(X, summing(a,b))
>
> I am a R beginner.  I am looking for a more efficient R code.
>
> Any help or advice will be appreciated.
>
> Taka,
>
> ______________________________________________
> R-help@stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
> http://www.R-project.org/posting-guide.html
>


-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390 (Cell)
+1 513 247 0281 (Home)

What is the problem you are trying to solve?

	[[alternative HTML version deleted]]

Little algebra will convince you that your 'summing' function is just
equal to:
sum(a) + sum(b)*X
So, it is very difficult to get it any faster than:
plot(X, sum(a)+sum(b)*X)

And, by the way, most of the execution time is spent plotting, not
computing the average:
> system.time({y1 <- summing(a,b)})
[1] 0.002 0.000 0.001 0.000 0.000
> system.time({y2 = sum(a)+sum(b)*X})
[1] 0 0 0 0 0
> all.equal(y1,y2)
[1] TRUE
> system.time(plot(X,y2))
[1] 0.019 0.002 0.051 0.000 0.000
>

Gardar



On Mon, 2006-06-26 at 17:21, Taka Matzmoto wrote:
> Dear R-users
> 
> I have four simple linear models, which are all in the form of a*X+b
> The estimated parameter vectors are
> 
> a <- c(1,2,3,4)
> b <- c(4,3,2,1)
> 
> My goal is to draw a plot where x-axis is X (range from -100 to 100) and 
> y-axis is the sum of
> all four linear models
> 
> X <- seq(-100,100, length=10000)
> plot(X, sum of the four linear functions)
> 
> I started with a function for summing
> 
> summing <- function(a,b)
> {temp <-0;
> for (i in 1:length(a))
> temp <- temp + a[i]*X+b[i]
> }
> 
> plot(X, summing(a,b))
> 
> I am a R beginner.  I am looking for a more efficient R code.
> 
> Any help or advice will be appreciated.
> 
> Taka,
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html