R help - Jul 2010 - how to calculate the product of every two elements in two vectors

Thanks in advance!

A=c(1, 2,3)
B=c (9, 10, 11, 12)

I want to get C=c(1*9, 1*10, 1*11, 1*12, ....., 3*9, 3*10, 3*11, 3*12)?
C is still a vector with 12 elements
Is there a way to do that?
-- 
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as.vector(t(outer(A, B)))
[1]  9 10 11 12 18 20 22 24 27 30 33 36

HTH,
Dennis

On Fri, Jul 23, 2010 at 8:11 AM, aegea <gcheer3@gmail.com> wrote:
>
> Thanks in advance!
>
> A=c(1, 2,3)
> B=c (9, 10, 11, 12)
>
> I want to get C=c(1*9, 1*10, 1*11, 1*12, ....., 3*9, 3*10, 3*11, 3*12)?
> C is still a vector with 12 elements
> Is there a way to do that?
> --
> View this message in context:
>
http://r.789695.n4.nabble.com/how-to-calculate-the-product-of-every-two-elements-in-two-vectors-tp2300299p2300299.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help@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.
>
	[[alternative HTML version deleted]]

Try this:

 c(as.matrix(B) %*% A)

On Fri, Jul 23, 2010 at 12:11 PM, aegea <gcheer3@gmail.com> wrote:
>
> Thanks in advance!
>
> A=c(1, 2,3)
> B=c (9, 10, 11, 12)
>
> I want to get C=c(1*9, 1*10, 1*11, 1*12, ....., 3*9, 3*10, 3*11, 3*12)?
> C is still a vector with 12 elements
> Is there a way to do that?
> --
> View this message in context:
>
http://r.789695.n4.nabble.com/how-to-calculate-the-product-of-every-two-elements-in-two-vectors-tp2300299p2300299.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help@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.
>


-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O

	[[alternative HTML version deleted]]

On Fri, Jul 23, 2010 at 11:11 AM, aegea <gcheer3 at gmail.com>
wrote:
>
> Thanks in advance!
>
> A=c(1, 2,3)
> B=c (9, 10, 11, 12)
>
> I want to get C=c(1*9, 1*10, 1*11, 1*12, ....., 3*9, 3*10, 3*11, 3*12)?
> C is still a vector with 12 elements
> Is there a way to do that?
Here are yet a few more.  The first one is the only one so far that
uses a single function and the last two are slight variations of ones
already posted.

kronecker(A, B)

c(tcrossprod(B, A))

c(outer(B, A))

c(B %o% A)

Here is a speed comparison.  The fastest are as.matrix, %outer% and
%o% .  They are so close that random fluctuations might easily change
their order and since %o% involves the least keystrokes that one might
be a good overall choice.  Although not among the fastest the
kronecker solution is the simplest since it only involves a single
function call so it might be preferred on that count.
> A <- B <- 1:400
> out <- benchmark(
+ as.matrix =  c(as.matrix(B) %*% A),
+ crossprod = c(tcrossprod(B, A)),
+ outer = c(outer(B, A)),
+ o = c(B %o% A),
+ kronecker = kronecker(A, B),
+ touter = as.vector(t(outer(A, B))))
> out[order(out$relative), ]
       test replications elapsed relative user.self sys.self
user.child sys.child
1 as.matrix          100    0.92 1.000000      0.62     0.28
NA        NA
3     outer          100    0.93 1.010870      0.59     0.35
NA        NA
4         o          100    0.94 1.021739      0.66     0.28
NA        NA
2 crossprod          100    1.11 1.206522      0.67     0.43
NA        NA
5 kronecker          100    1.45 1.576087      1.25     0.21
NA        NA
6    touter          100    1.84 2.000000      1.40     0.43
NA        NA

Hi

r-help-bounces at r-project.org napsal dne 23.07.2010 17:11:43:
> 
> Thanks in advance!
> 
> A=c(1, 2,3)
> B=c (9, 10, 11, 12)
> 
> I want to get C=c(1*9, 1*10, 1*11, 1*12, ....., 3*9, 3*10, 3*11, 3*12)?
> C is still a vector with 12 elements
> Is there a way to do that?
Maybe

as.vector(t(outer(A,B)))

Regards
Petr

> -- 
> View this message in context: 
http://r.789695.n4.nabble.com/how-to-calculate-
> the-product-of-every-two-elements-in-two-vectors-tp2300299p2300299.html
> Sent from the R help mailing list archive at Nabble.com.
> 
> ______________________________________________
> 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.