[R] 3D array

[Ravi Varadhan]

The following will work:

apply(my.array, c(1,2), mean)

Ravi.

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Ravi Varadhan, Ph.D.

Assistant Professor, The Center on Aging and Health

Division of Geriatric Medicine and Gerontology 

Johns Hopkins University

Ph: (410) 502-2619

Fax: (410) 614-9625

Email: rvaradhan at jhmi.edu

Webpage:  http://www.jhsph.edu/agingandhealth/People/Faculty/Varadhan.html

 

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-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On
Behalf Of threshold
Sent: Monday, December 03, 2007 7:25 PM
To: r-help at r-project.org
Subject: [R] 3D array


Hi, I deal with 3D array say:

, , 1

     [,1] [,2] [,3] [,4] [,5]
[1,]    1    4    7   10   13
[2,]    2    5    8   11   14
[3,]    3    6    9   12   15

, , 2

     [,1] [,2] [,3] [,4] [,5]
[1,]   16   19   22   25   28
[2,]   17   20   23   26   29
[3,]   18   21   24   27   30

, , 3

     [,1] [,2] [,3] [,4] [,5]
[1,]   31   34   37   40   43
[2,]   32   35   38   41   44
[3,]   33   36   39   42   45

I want to calculate means in the cells with respect to dimention 3rd so for
example (1+16+31)/3 or (15+30+45)/3  AND avoid taking zeros into account.

I did it with a loop but I guess there is the other more straightforward
method. will be very grateful for help...

best, rob
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