[R] (newbie) sum for certain number of rows

[kelvin lau]

Thanks. I tried it and it worked wonderful.


Wishing for the "DAY' to come. Life needs to be 'reset'.


--- On Wed, 7/15/09, Dimitris Rizopoulos <d.rizopoulos at erasmusmc.nl> wrote:

> From: Dimitris Rizopoulos <d.rizopoulos at erasmusmc.nl>
> Subject: Re: [R] (newbie) sum for certain number of rows
> To: "kelvin lau" <kelvinlhk at yahoo.com>
> Cc: r-help at r-project.org
> Date: Wednesday, July 15, 2009, 6:25 PM
> one way is the following:
> 
> dat <- read.table(textConnection(
> "0 0 1 0 0 1 0 1
> 0 0 0 0 0 0 0 0
> 1 0 0 1 1 0 1 0
> 0 0 1 1 0 0 0 0
> 1 1 0 0 0 0 1 1
> 0 0 0 0 0 0 0 0
> 0 1 0 1 1 0 1 0
> 1 1 1 1 1 1 1 1
> 1 1 1 1 1 1 1 1"
> ))
> closeAllConnections()
> 
> k <- 3
> ind <- rep(seq(1, nrow(dat)/k), each = k)
> rowsum(dat, ind)
> 
> 
> I hope it helps.
> 
> Best,
> Dimitris
> 
> 
> kelvin lau wrote:
> > I have following data in a data.csv file separated by
> space
> > 
> > 0 0 1 0 0 1 0 1
> > 0 0 0 0 0 0 0 0
> > 1 0 0 1 1 0 1 0
> > 0 0 1 1 0 0 0 0
> > 1 1 0 0 0 0 1 1
> > 0 0 0 0 0 0 0 0
> > 0 1 0 1 1 0 1 0
> > 1 1 1 1 1 1 1 1
> > 1 1 1 1 1 1 1 1
> > etc...
> > 
> > I wish to calculate the sum of each column for certain
> number of rows. For example if I want sum of the data after
> each 3 rows, it should display
> > 1 0 1 1 1 1 1 1
> > 1 1 1 1 0 0 1 1
> > 2 3 2 3 3 2 3 2
> > 
> > So far, this is what I have done
> > xx<-read.table("data.csv",header=FALSE)
> > ss<-t(apply(xx,2,sum)) # which displayed the sum of
> all rows
> > 
> > I tried my best to look for solution on the Internet
> but so far haven't managed to find it. I am extremely
> grateful if someone can point me how to go about it.
> Thanks.
> > 
> > Kelvin
> > 
> > ______________________________________________
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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
>