[R] Calculateing means

[Khan, Sohail]

Thanks. But aggregate will work on rows or columns.  I need to calculate mean for subsets of rows in a matrix
I.E.

Indx	 x1 	x2 	x3	 x4	x5 	x6 	x7 	x8 	x9
1	25	30	15	8	12	9	18	21	89
2	52	35	42	74	65	20	28	32	12
3	12	35	33	88	12	52	32	32	18
4	25	25	16	23	89	21	21	21	42
........................................
...................................
I would like to calculate means for x1-x3, x4-x6, x7-x9
For each row.

-Sohail


-----Original Message-----
From: John Kane [mailto:jrkrideau at inbox.com] 
Sent: Friday, November 16, 2012 4:35 PM
To: Khan, Sohail; 'r-help at r-project.org'
Subject: RE: [R] Calculateing means

?aggregate will do it.

x <- data.frame( height= c(50, 174, 145, 200, 210, 140, 175), age_group=c(1,2,2,1,1,2,1), 
                     ville= c(1,2,3,1,2,3,1))

aggregate(x$height,list(x$age_group, x$ville), mean)

or have a look at the plyr or datatable packages.

John Kane
Kingston ON Canada


> -----Original Message-----
> From: skhan30 at nshs.edu
> Sent: Fri, 16 Nov 2012 15:58:17 -0500
> To: r-help at r-project.org
> Subject: [R] Calculateing means
> 
> 
> Dear List,
> 
> I have a data matrix with 570 columns containing 95 (samples) with 6 
> replicates each.
> How can I calculate the mean of the replicates for 95 samples?
> Thank you.
> 
> 
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The information contained in this electronic e-mail transmission and any attachments are intended only for the use of the individual or entity to whom or to which it is addressed, and may contain information that is privileged, confidential and exempt from disclosure under applicable law. If the reader of this communication is not the intended recipient, or the employee or agent responsible for delivering this communication to the intended recipient, you are hereby notified that any dissemination, distribution, copying or disclosure of this communication and any attachment is strictly prohibited. If you have received this transmission in error, please notify the sender immediately by telephone and electronic mail, and delete the original communication and any attachment from any computer, server or other electronic recording or storage device or medium. Receipt by anyone other than the intended recipient is not a waiver of any attorney-client, physician-patient or other privilege.