On Apr 16, 2012, at 3:26 PM, David Winsemius wrote:
On Apr 16, 2012, at 2:43 PM, David A Vavra wrote:
Thanks Petr,
I'm after T1 + T2 + T3 + ...
Which would be one number ... i.e. the result you originally said
you did not want.
and your solution is giving a list of n items
each containing sum(T[i]). I guess I should have been clearer in
stating
what I need.
Or even now you _could_ be clearer. Do you want successive partial
sums? That would yield to:
Reduce("+", listoftables, accumaulate=TRUE)
If Dunlap's interpretation is corect then consder this
L <- lapply(1:50000, function(i) array(i:(i+7), c(2,2,2)))
system.time({final <- L[[1]]
for(i in seq_along(L)[-1]) final <- final + L[[i]]
final} )
# user system elapsed
# 0.179 0.002 0.187
system.time(Reduce("+", L))
# user system elapsed
# 0.150 0.002 0.157
> identical(Reduce("+", L), final)
[1] TRUE
Cheers,
DAV
-----Original Message-----
From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org
] On
Behalf Of Petr Savicky
Sent: Monday, April 16, 2012 11:07 AM
To: r-help@r-project.org
Subject: Re: [R] Effeciently sum 3d table
On Mon, Apr 16, 2012 at 10:28:43AM -0400, David A Vavra wrote:
I have a large number of 3d tables that I wish to sum
Is there an efficient way to do this? Or perhaps a function I can
call?
I tried using do.call("sum",listoftables) but that returns a
single value.
So far, it seems only a loop will do the job.
Hi.
Use lapply(), for example
listoftables <- list(array(1:8, dim=c(2, 2, 2)), array(2:9,
dim=c(2, 2,
2)))
lapply(listoftables, sum)
[[1]]
[1] 36
[[2]]
[1] 44
Hope this helps.
Petr Savicky.
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______________________________________________
R-help@r-project.org mailing list
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
David Winsemius, MD
West Hartford, CT
______________________________________________
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.
David Winsemius, MD
West Hartford, CT
______________________________________________
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.
