[R] sum of list elements
Dear list, I have some difficulty in manipulating list elements. More specifically, I am performing svm regression and have a list of lists, called pred.svm. The elements of the second list are 3D arrays. Thus I have pred.svm[[i]][[j]], with 1=i=5 and 1=j=20. I want to take the sum of the elements a specific array dimension across all j, for one i. Mathematically speaking, I want to calculate *W* as: *W = pred.svm[[i]][[1]][1,2,5] + pred.svm[[i]][[2]][1,2,5]+ pred.svm[[i]][[3]][1,2,5]+...+ pred.svm[[i]][[20]][1,2,5]* I have tried to apply the *lapply() *function but it seems that its arguments can only be vector elements of a list...Do I need to convert the array data to vector data? Any advice would be very welcome! Thanks a lot, Eleni [[alternative HTML version deleted]] __ 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.
Re: [R] sum of list elements
do these lists contain 3D arrays of the same dimensions? If yes, then
you could use
Reduce(+, pred.svm[[i]])[1,2,5]
otherwise a for-loop will also be clear and efficient, e.g.,
W - pred.svm[[i]][[1]][1,2,5]
for (j in 2:20) {
W - W + pred.svm[[i]][[j]][1,2,5]
}
I hope it helps.
Best,
Dimitris
On 3/4/2010 4:02 PM, Eleni Christodoulou wrote:
Dear list,
I have some difficulty in manipulating list elements. More specifically, I
am performing svm regression and have a list of lists, called pred.svm. The
elements of the second list are 3D arrays. Thus I have pred.svm[[i]][[j]],
with 1=i=5 and 1=j=20.
I want to take the sum of the elements a specific array dimension across all
j, for one i. Mathematically speaking, I want to calculate *W* as:
*W = pred.svm[[i]][[1]][1,2,5] + pred.svm[[i]][[2]][1,2,5]+
pred.svm[[i]][[3]][1,2,5]+...+ pred.svm[[i]][[20]][1,2,5]*
I have tried to apply the *lapply() *function but it seems that its
arguments can only be vector elements of a list...Do I need to convert the
array data to vector data?
Any advice would be very welcome!
Thanks a lot,
Eleni
[[alternative HTML version deleted]]
__
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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.
--
Dimitris Rizopoulos
Assistant Professor
Department of Biostatistics
Erasmus University Medical Center
Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands
Tel: +31/(0)10/7043478
Fax: +31/(0)10/7043014
__
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
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Re: [R] sum of list elements
Thank you Dimitris!
I have 3D arrays of the same dimensions, so Reduce worked...
Best,
Eleni
On Thu, Mar 4, 2010 at 5:13 PM, Dimitris Rizopoulos
d.rizopou...@erasmusmc.nl wrote:
do these lists contain 3D arrays of the same dimensions? If yes, then you
could use
Reduce(+, pred.svm[[i]])[1,2,5]
otherwise a for-loop will also be clear and efficient, e.g.,
W - pred.svm[[i]][[1]][1,2,5]
for (j in 2:20) {
W - W + pred.svm[[i]][[j]][1,2,5]
}
I hope it helps.
Best,
Dimitris
On 3/4/2010 4:02 PM, Eleni Christodoulou wrote:
Dear list,
I have some difficulty in manipulating list elements. More specifically, I
am performing svm regression and have a list of lists, called pred.svm.
The
elements of the second list are 3D arrays. Thus I have pred.svm[[i]][[j]],
with 1=i=5 and 1=j=20.
I want to take the sum of the elements a specific array dimension across
all
j, for one i. Mathematically speaking, I want to calculate *W* as:
*W = pred.svm[[i]][[1]][1,2,5] + pred.svm[[i]][[2]][1,2,5]+
pred.svm[[i]][[3]][1,2,5]+...+ pred.svm[[i]][[20]][1,2,5]*
I have tried to apply the *lapply() *function but it seems that its
arguments can only be vector elements of a list...Do I need to convert the
array data to vector data?
Any advice would be very welcome!
Thanks a lot,
Eleni
[[alternative HTML version deleted]]
__
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.
--
Dimitris Rizopoulos
Assistant Professor
Department of Biostatistics
Erasmus University Medical Center
Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands
Tel: +31/(0)10/7043478
Fax: +31/(0)10/7043014
[[alternative HTML version deleted]]
__
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.
Re: [R] sum of list elements
My guess is that the original
poster is expecting a matrix
not a scalar. If so, then:
Reduce('+', a)
[,1] [,2] [,3]
[1,]300
[2,]030
[3,]003
Patrick Burns
patr...@burns-stat.com
+44 (0)20 8525 0696
http://www.burns-stat.com
(home of The R Inferno and A Guide for the Unwilling S User)
David Winsemius wrote:
On Jul 2, 2009, at 11:24 PM, David Winsemius wrote:
On Jul 2, 2009, at 10:20 PM, Ivo Shterev wrote:
a = list(diag(3), diag(3), diag(3))
a = list(diag(3), diag(3), diag(3))
sum(unlist(a))
[1] 9
Also:
sum(sapply(a,I))
[1] 9
David Winsemius, MD
Heritage Laboratories
West Hartford, CT
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and provide commented, minimal, self-contained, reproducible code.
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[R] sum of list elements
Dear All, Is there an automatic way to sum the elements of a list? For example given a = list(diag(3), diag(3), diag(3)) to obtain b=a[1]+a[2]+a[3]. Thanks Ivo __ 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.
Re: [R] sum of list elements
I think you are asking for Reduce Reduce(`+`, a) [,1] [,2] [,3] [1,]300 [2,]030 [3,]003 You might be asking for do.call with some function's name as its first argument. do.call(sum, a) [1] 9 __ 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.
Re: [R] sum of list elements
On Jul 2, 2009, at 10:20 PM, Ivo Shterev wrote: a = list(diag(3), diag(3), diag(3)) a = list(diag(3), diag(3), diag(3)) sum(unlist(a)) [1] 9 David Winsemius, MD Heritage Laboratories 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.
Re: [R] sum of list elements
On Jul 2, 2009, at 11:24 PM, David Winsemius wrote: On Jul 2, 2009, at 10:20 PM, Ivo Shterev wrote: a = list(diag(3), diag(3), diag(3)) a = list(diag(3), diag(3), diag(3)) sum(unlist(a)) [1] 9 Also: sum(sapply(a,I)) [1] 9 David Winsemius, MD Heritage Laboratories 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.
