subject:"\[R\] Transfer a 3\-dimensional array to a matrix in R"

Re: [R] Transfer a 3-dimensional array to a matrix in R

2015-10-21 Thread Chunyu Dong

thank you very much! Both the two methods work well for my data.


Best wishes,


Chunyu








At 2015-10-20 19:48:18, "William Dunlap"  wrote:
>Or use aperm() (array index permuation):
>  > array(aperm(x, c(2,1,3)), c(6,3))
>   [,1] [,2] [,3]
>  [1,]17   13
>  [2,]4   10   16
>  [3,]28   14
>  [4,]5   11   17
>  [5,]39   15
>  [6,]6   12   18
>
>Bill Dunlap
>TIBCO Software
>wdunlap tibco.com
>
>
>On Tue, Oct 20, 2015 at 11:31 AM, John Laing  wrote:
>>> x <- array(1:18, dim=c(3, 2, 3))
>>> x
>> , , 1
>>
>>  [,1] [,2]
>> [1,]14
>> [2,]25
>> [3,]36
>>
>> , , 2
>>
>>  [,1] [,2]
>> [1,]7   10
>> [2,]8   11
>> [3,]9   12
>>
>> , , 3
>>
>>  [,1] [,2]
>> [1,]   13   16
>> [2,]   14   17
>> [3,]   15   18
>>
>>> apply(x, 3, t)
>>  [,1] [,2] [,3]
>> [1,]17   13
>> [2,]4   10   16
>> [3,]28   14
>> [4,]5   11   17
>> [5,]39   15
>> [6,]6   12   18
>>
>>
>> On Tue, Oct 20, 2015 at 12:39 PM, Chunyu Dong 
>> wrote:
>>
>>> Hello!
>>>
>>>
>>> Recently I am trying to transfer a large 3-dimensional array to a matrix.
>>> For example, a array like:
>>> , , 1
>>>  [,1] [,2]
>>> [1,]14
>>> [2,]25
>>> [3,]36
>>> , , 2
>>>  [,1] [,2]
>>> [1,]7   10
>>> [2,]8   11
>>> [3,]9   12
>>> , , 3
>>>  [,1] [,2]
>>> [1,]   13   16
>>> [2,]   14   17
>>> [3,]   15   18
>>>
>>>
>>> I would like to transfer it to a matrix like:
>>> 17  13
>>> 41016
>>> 28  14
>>> 51117
>>> 39  15
>>> 61218
>>>
>>>
>>> Could you tell me how to do it in R ? Thank you very much!
>>>
>>>
>>> Best regards,
>>> Chunyu
>>>
>>>
>>>
>>>
>>>
>>> [[alternative HTML version deleted]]
>>>
>>> __
>>> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
>>> 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]]
>>
>> __
>> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> 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]]

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Re: [R] Transfer a 3-dimensional array to a matrix in R

2015-10-20 Thread William Dunlap

Or use aperm() (array index permuation):
  > array(aperm(x, c(2,1,3)), c(6,3))
   [,1] [,2] [,3]
  [1,]17   13
  [2,]4   10   16
  [3,]28   14
  [4,]5   11   17
  [5,]39   15
  [6,]6   12   18

Bill Dunlap
TIBCO Software
wdunlap tibco.com


On Tue, Oct 20, 2015 at 11:31 AM, John Laing  wrote:
>> x <- array(1:18, dim=c(3, 2, 3))
>> x
> , , 1
>
>  [,1] [,2]
> [1,]14
> [2,]25
> [3,]36
>
> , , 2
>
>  [,1] [,2]
> [1,]7   10
> [2,]8   11
> [3,]9   12
>
> , , 3
>
>  [,1] [,2]
> [1,]   13   16
> [2,]   14   17
> [3,]   15   18
>
>> apply(x, 3, t)
>  [,1] [,2] [,3]
> [1,]17   13
> [2,]4   10   16
> [3,]28   14
> [4,]5   11   17
> [5,]39   15
> [6,]6   12   18
>
>
> On Tue, Oct 20, 2015 at 12:39 PM, Chunyu Dong 
> wrote:
>
>> Hello!
>>
>>
>> Recently I am trying to transfer a large 3-dimensional array to a matrix.
>> For example, a array like:
>> , , 1
>>  [,1] [,2]
>> [1,]14
>> [2,]25
>> [3,]36
>> , , 2
>>  [,1] [,2]
>> [1,]7   10
>> [2,]8   11
>> [3,]9   12
>> , , 3
>>  [,1] [,2]
>> [1,]   13   16
>> [2,]   14   17
>> [3,]   15   18
>>
>>
>> I would like to transfer it to a matrix like:
>> 17  13
>> 41016
>> 28  14
>> 51117
>> 39  15
>> 61218
>>
>>
>> Could you tell me how to do it in R ? Thank you very much!
>>
>>
>> Best regards,
>> Chunyu
>>
>>
>>
>>
>>
>> [[alternative HTML version deleted]]
>>
>> __
>> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> 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]]
>
> __
> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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.

__
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
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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] Transfer a 3-dimensional array to a matrix in R

2015-10-20 Thread Dénes Tóth


Hi,

Bill was faster than me in suggesting aperm() instead of apply(), 
however, his solution is still suboptimal. Try to avoid array(), and

set the dimensions directly if possible.



fn1 <- function(x) {
apply(x, 3, t)
}


fn2 <- function(x) {
array(aperm(x, c(2, 1, 3)), c(prod(dim(x)[1:2]), dim(x)[3]))
}

fn3 <- function(x) {
x <- aperm(x, c(2, 1, 3))
dim(x) <- c(prod(dim(x)[1:2]), dim(x)[3])
x
}

# check that the functions return the same
x <- array(1:18, dim=c(3, 2, 3))
stopifnot(identical(fn1(x), fn2(x)))
stopifnot(identical(fn1(x), fn3(x)))

# create two larger arrays, play with the size of the 3rd dimension
x <- array(1:18e4, dim=c(3, 2e1, 3e3))
y <- array(1:18e4, dim=c(3e3, 2e1, 3))

# and the timing:
library(microbenchmark)
microbenchmark(fn1(x), fn2(x), fn3(x), fn1(y), fn2(y), fn3(y), times = 100L)

---

Conclusion:
fn3() is about 3x as fast as fn2(), and fn1() can be extremely 
inefficient if dim(x)[3] is large.



HTH,
  Denes




On 10/20/2015 08:48 PM, William Dunlap wrote:

Or use aperm() (array index permuation):
   > array(aperm(x, c(2,1,3)), c(6,3))
[,1] [,2] [,3]
   [1,]17   13
   [2,]4   10   16
   [3,]28   14
   [4,]5   11   17
   [5,]39   15
   [6,]6   12   18

Bill Dunlap
TIBCO Software
wdunlap tibco.com


On Tue, Oct 20, 2015 at 11:31 AM, John Laing  wrote:

x <- array(1:18, dim=c(3, 2, 3))
x

, , 1

  [,1] [,2]
[1,]14
[2,]25
[3,]36

, , 2

  [,1] [,2]
[1,]7   10
[2,]8   11
[3,]9   12

, , 3

  [,1] [,2]
[1,]   13   16
[2,]   14   17
[3,]   15   18


apply(x, 3, t)

  [,1] [,2] [,3]
[1,]17   13
[2,]4   10   16
[3,]28   14
[4,]5   11   17
[5,]39   15
[6,]6   12   18


On Tue, Oct 20, 2015 at 12:39 PM, Chunyu Dong 
wrote:


Hello!


Recently I am trying to transfer a large 3-dimensional array to a matrix.
For example, a array like:
, , 1
  [,1] [,2]
[1,]14
[2,]25
[3,]36
, , 2
  [,1] [,2]
[1,]7   10
[2,]8   11
[3,]9   12
, , 3
  [,1] [,2]
[1,]   13   16
[2,]   14   17
[3,]   15   18


I would like to transfer it to a matrix like:
17  13
41016
28  14
51117
39  15
61218


Could you tell me how to do it in R ? Thank you very much!


Best regards,
Chunyu





 [[alternative HTML version deleted]]

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R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
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]]

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R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
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and provide commented, minimal, self-contained, reproducible code.


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and provide commented, minimal, self-contained, reproducible code.



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and provide commented, minimal, self-contained, reproducible code.

[R] Transfer a 3-dimensional array to a matrix in R

2015-10-20 Thread Chunyu Dong

Hello!


Recently I am trying to transfer a large 3-dimensional array to a matrix. For 
example, a array like:
, , 1
 [,1] [,2]
[1,]14
[2,]25
[3,]36
, , 2
 [,1] [,2]
[1,]7   10
[2,]8   11
[3,]9   12
, , 3
 [,1] [,2]
[1,]   13   16
[2,]   14   17
[3,]   15   18


I would like to transfer it to a matrix like:
17  13
41016
28  14
51117
39  15
61218


Could you tell me how to do it in R ? Thank you very much!


Best regards,
Chunyu





[[alternative HTML version deleted]]

__
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
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] Transfer a 3-dimensional array to a matrix in R

2015-10-20 Thread John Laing

> x <- array(1:18, dim=c(3, 2, 3))
> x
, , 1

 [,1] [,2]
[1,]14
[2,]25
[3,]36

, , 2

 [,1] [,2]
[1,]7   10
[2,]8   11
[3,]9   12

, , 3

 [,1] [,2]
[1,]   13   16
[2,]   14   17
[3,]   15   18

> apply(x, 3, t)
 [,1] [,2] [,3]
[1,]17   13
[2,]4   10   16
[3,]28   14
[4,]5   11   17
[5,]39   15
[6,]6   12   18


On Tue, Oct 20, 2015 at 12:39 PM, Chunyu Dong 
wrote:

> Hello!
>
>
> Recently I am trying to transfer a large 3-dimensional array to a matrix.
> For example, a array like:
> , , 1
>  [,1] [,2]
> [1,]14
> [2,]25
> [3,]36
> , , 2
>  [,1] [,2]
> [1,]7   10
> [2,]8   11
> [3,]9   12
> , , 3
>  [,1] [,2]
> [1,]   13   16
> [2,]   14   17
> [3,]   15   18
>
>
> I would like to transfer it to a matrix like:
> 17  13
> 41016
> 28  14
> 51117
> 39  15
> 61218
>
>
> Could you tell me how to do it in R ? Thank you very much!
>
>
> Best regards,
> Chunyu
>
>
>
>
>
> [[alternative HTML version deleted]]
>
> __
> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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]]

__
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
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] Transfer a 3-dimensional array to a matrix in R

Re: [R] Transfer a 3-dimensional array to a matrix in R

Re: [R] Transfer a 3-dimensional array to a matrix in R

[R] Transfer a 3-dimensional array to a matrix in R

Re: [R] Transfer a 3-dimensional array to a matrix in R

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