From: John Kane <jrkrideau_at_yahoo.ca>

Date: Mon, 03 Mar 2008 12:47:26 -0500 (EST)

(Thanks to Mark Leeds for the lapply approach)

R-help_at_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. Received on Mon 03 Mar 2008 - 18:27:36 GMT

Date: Mon, 03 Mar 2008 12:47:26 -0500 (EST)

If I understand you correctly what you want to do is
do t-test (mu=0) for each column of the data.

Treating the data as a data.frame rather than a matrix you can do something like this and then pick out the p-values but with 140 t-tests I don't know what you'll get in terms of anything meaninful.

aa <- data.frame(a=rnorm(25, 5, 2), b=rnorm(1:25,
0,1))

mytea <- apply(aa, 2, t.test)

tresults <- lapply(mytea, function(.tres) {

data.frame(t.value=.tres[1],dfs=.tres[2],conf.int1=.tres$conf.int[1],conf.int2= .tres$conf.int[2],p.value=.tres[3])

})

finalresults <- do.call(rbind, tresults)

(Thanks to Mark Leeds for the lapply approach)

- Keizer_71 <christophe.lo_at_gmail.com> wrote:

*>
*

> Hi Everyone,

*>
**> I need some simple help.
**>
**> Here are my codes
**>
**> ##########will give me 10000
**> probesets####################
**> data.sub =
*

>

data.matrix[order(variableprobe,decreasing=TRUE),][1:10000,]

> dim(data.sub)

*> data_output<-write.table(data.sub, file =
**> "c://data_output.csv", sep = ",",
**> col.names = NA)
**>
**> When i export to excel, it shows me this. This is
**> just a short version.
**> There are 1000 rows and 140 columns
**>
**> Sample_1_D Sample_1_C Sample_2_D Sample_2_C
**> 1 2.425509867 11.34031409 11.46868531 11.75741478
**>
**>
**> Here is my question: How do create a new row and
**> calculate the t-test so
**> that it will give me the p-value
**>
**> Here is what i am looking for. The p-value is not
**> correct but just an
**> example. It needs to calculate the entire each row.
**> There are 10000 rows and
**> 140 columns.
**>
**> thanks
**> Kei
**>
**> Sample_1_D Sample_1_C Sample_2_D Sample_2_C
**> p-value
**> 1 2.425509867 11.34031409 11.46868531 11.75741478
**> .00341111
**>
**> I tried something like this.
**>
**> t.test(data.sub,mu=0)
**>
**> I am pretty new to R. I think it is showing me the
**> entire p-value.
**>
**>
**>
**> --
**> View this message in context:
*

>

http://www.nabble.com/Calculating-the-t-test-for-each-row-tp15808716p15808716.html

> Sent from the R help mailing list archive at

*> Nabble.com.
**>
**> ______________________________________________
**> R-help_at_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.
*

>

R-help_at_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. Received on Mon 03 Mar 2008 - 18:27:36 GMT

Archive maintained by Robert King, hosted by
the discipline of
statistics at the
University of Newcastle,
Australia.

Archive generated by hypermail 2.2.0, at Mon 03 Mar 2008 - 18:30:20 GMT.

*
Mailing list information is available at https://stat.ethz.ch/mailman/listinfo/r-help.
Please read the posting
guide before posting to the list.
*