# Re: [R] How to simplify

From: Dimitris Rizopoulos <dimitris.rizopoulos_at_med.kuleuven.be>
Date: Thu 08 Dec 2005 - 02:10:39 EST

assuming that you have the same number of measurements in each sub-data.frame, you could use something like:

cal <- lapply(1:10, function(x) data.frame(time = c(0, 0.5, 1, 2, 4, 6, 8, 10), X1 = rnorm(8, 10:3)))
##############
rowMeans(as.data.frame(lapply(cal, "[", "X1")))

I hope it helps.

Best,
Dimitris

Dimitris Rizopoulos
Ph.D. Student
Biostatistical Centre
School of Public Health
Catholic University of Leuven

```Tel: +32/(0)16/336899
Fax: +32/(0)16/337015
Web: http://www.med.kuleuven.be/biostat/
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```
• Original Message ----- From: "Rhett Eckstein" <glaxowell@gmail.com> To: <r-help@stat.math.ethz.ch> Sent: Wednesday, December 07, 2005 3:38 PM Subject: [R] How to simplify

> Dear list,
> I have a list containing parameters (time and X1), and have "n"
> similar data set like
> the following:
>> cal
> [[1]]
> time X1
> 1 0.0 10.006306
> 2 0.5 9.433443
> 3 1.0 8.893405
> 4 2.0 7.904274
> 5 4.0 6.243807
> 6 6.0 4.932158
> 7 8.0 3.896049
> 8 10.0 3.077604
>
> [[2]]
> time X1
> 1 0.0 10.015972
> 2 0.5 9.460064
> 3 1.0 8.935039
> 4 2.0 7.970755
> 5 4.0 6.343151
> 6 6.0 5.047900
> 7 8.0 4.017131
> 8 10.0 3.196856
>
> [[3]]
> time X1
> 1 0.0 9.985741
> 2 0.5 9.552583
> 3 1.0 9.138239
> 4 2.0 8.362664
> 5 4.0 7.003394
> 6 6.0 5.865057
> 7 8.0 4.911747
> 8 10.0 4.113382
>
> [[4]]
> .......
>
> [[n]]
> .......
>
> And I would like to put all X1( when time=0) together,
> time=0.5,1...
> are the same.
> then calculate the mean value.
>> a<-list()
>> b<-list()
>> c<-list()
>> d<-list()
>> e<-list()
> .......
>> for(i in 1:n){
> + a[[i]]<-cal[[i]][1,2]
> + b[[i]]<-cal[[i]][2,2]
> + c[[i]]<-cal[[i]][3,2]
> + d[[i]]<-cal[[i]][4,2]
> + e[[i]]<-cal[[i]][5,2]
> + .........
> }
>>mean.a<-(a[[1]][1]+a[[2]][1]+a[[3]][1]+.....)/n
>>mean.b<-(b[[1]][1]+b[[2]][1]+b[[3]][1]+.....)/n
>>mean.c<-(c[[1]][1]+c[[2]][1]+c[[3]][1]+.....)/n
>>mean.d<-(d[[1]][1]+d[[2]][1]+d[[3]][1]+.....)/n
>>.............
>>xy<-c(mean.a,mean.b,mean.c,mean.d,........)
> But the way I use seem not very smart.
> So please give me some hints to the simplify this.
> Sincerely!!
>
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