R help - Jun 2009 - code that will use two data sets which differ in size.

Hi all,

This is a really basic question but I can't figure it out.

I am trying to write a piece of code that will  use two datasets, z and m..
This code is meant to assign the mean of selected values in dataset m to a new
column z$c in datset z but the rows and columns of the two data sets differ.

I managed to write this down but think I am missing something standard but
basic,I will really appreciate if someone could point out where I' am going
wrong or help me out with a piece of code for this.Google did not help me even
and the R manuals gave me hints.

"The shoulders will never grow beyond the head".

for (k in 1:nrow(z))
+ for (g in 1:nrow(m))
+ for (l in 1:3)
+ for (j in 15:43){
+ z$ccs[k]<-mean(m[m$soi[g]==l&m$week[g]==j,]$CCS,na.rm=TRUE)}









      
	[[alternative HTML version deleted]]

Petr Pikal
petr.pikal at precheza.cz
724008364, 581252140, 581252257


r-help-bounces at r-project.org napsal dne 26.06.2009 05:31:27:
> Hi all,
> 
> This is a really basic question but I can't figure it out.
> 
> I am trying to write a piece of code that will  use two datasets, z and 
m..
> This code is meant to assign the mean of selected values in dataset m to 
a new
> column z$c in datset z but the rows and columns of the two data sets 
differ.
> 
> I managed to write this down but think I am missing something standard 
but 
> basic,I will really appreciate if someone could point out where I' am 
going 
> wrong or help me out with a piece of code for this.Google did not help 
me even
> and the R manuals gave me hints.
> 
> "The shoulders will never grow beyond the head".
> 
> for (k in 1:nrow(z))
> + for (g in 1:nrow(m))
> + for (l in 1:3)
> + for (j in 15:43){
> + z$ccs[k]<-mean(m[m$soi[g]==l&m$week[g]==j,]$CCS,na.rm=TRUE)}
Maybe that I have no idea what is z I get an error too.
> for (k in 1:nrow(z))
+ + for (g in 1:nrow(m))
+ + for (l in 1:3)
+ + for (j in 15:43){
+ + z$ccs[k]<-mean(m[m$soi[g]==l&m$week[g]==j,]$CCS,na.rm=TRUE)}
Error in nrow(z) : object 'z' not found

What kind of error do you have?

If you do not post some reproducible example it would be quite difficult 
to understand what you want to get as a result. I believe some *apply 
trick could help but without knowing what you want it could be just rough 
guessing.

Regards
Petr
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
>    [[alternative HTML version deleted]]
> 
> ______________________________________________
> 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.

Hi ,

Thanks for the timely reply in,z is the larger dataframe and m is the
shorter dataframe.
The code took more than 2 hrs and I had to kill it.

Another way putting this question could be; how can I use th family of
(apply) funtions to get the summary of one of the variables based on two
factors?

Thanks again,


arnoldo wrote:
> 
> Hi all,
> 
> This is a really basic question but I can't figure it out.
> 
> I am trying to write a piece of code that will? use two datasets, z and
> m..
> This code is meant to assign the mean of selected values in dataset m to a
> new column z$c in datset z but the rows and columns of the two data sets
> differ.
> 
> I managed to write this down but think I am missing something standard but
> basic,I will really appreciate if someone could point out where I' am
> going wrong or help me out with a piece of code for this.Google did not
> help me even and the R manuals gave me hints.
> 
> "The shoulders will never grow beyond the head".
> 
> for (k in 1:nrow(z))
> + for (g in 1:nrow(m))
> + for (l in 1:3)
> + for (j in 15:43){
> + z$ccs[k]<-mean(m[m$soi[g]==l&m$week[g]==j,]$CCS,na.rm=TRUE)}
> 
> 
> 
> 
> 
> 
> 
> 
> 
>       
> 	[[alternative HTML version deleted]]
> 
> 
> ______________________________________________
> 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.
> 
> 
-- 
View this message in context:
http://www.nabble.com/code-that-will-use-two-data-sets-which-differ-in-size.-tp24214485p24239706.html
Sent from the R help mailing list archive at Nabble.com.

If I understand what you want, you simply want to calculate some means in one
data.frame and put some of them in another data.frame?
Data.frames are of unequal lenght but you know the indices for each. As long as
you know the indices the relative sizes should be irrelevant. Try something like
this.  It's a bit ugly but I think it will work

mydata <- data.frame(a = 1:10, b=11:20, c=21:30) # frame to get means
adat <- data.frame(dd=rnorm(20,5,2))         # target data.frame
mm <- (mydata[,2]+mydata[,3])/2; mm    #Calculate means
adat[c(1,3),2] <-  mm[c(2,7)]          #   Get means from vector into target

--- On Sun, 6/28/09, arnoldo <a_akem2001 at yahoo.co.uk> wrote:
> From: arnoldo <a_akem2001 at yahoo.co.uk>
> Subject: Re: [R] code that will use two data sets which differ in size.
> To: r-help at r-project.org
> Received: Sunday, June 28, 2009, 4:40 AM
> 
> Hi ,
> 
> Thanks for the timely reply in,z is the larger dataframe
> and m is the
> shorter dataframe.
> The code took more than 2 hrs and I had to kill it.
> 
> Another way putting this question could be; how can I use
> th family of
> (apply) funtions to get the summary of one of the variables
> based on two
> factors?
> 
> Thanks again,
> 
> 
> arnoldo wrote:
> > 
> > Hi all,
> > 
> > This is a really basic question but I can't figure it
> out.
> > 
> > I am trying to write a piece of code that will? use
> two datasets, z and
> > m..
> > This code is meant to assign the mean of selected
> values in dataset m to a
> > new column z$c in datset z but the rows and columns of
> the two data sets
> > differ.
> > 
> > I managed to write this down but think I am missing
> something standard but
> > basic,I will really appreciate if someone could point
> out where I' am
> > going wrong or help me out with a piece of code for
> this.Google did not
> > help me even and the R manuals gave me hints.
> > 
> > "The shoulders will never grow beyond the head".
> > 
> > for (k in 1:nrow(z))
> > + for (g in 1:nrow(m))
> > + for (l in 1:3)
> > + for (j in 15:43){
> > +
> z$ccs[k]<-mean(m[m$soi[g]==l&m$week[g]==j,]$CCS,na.rm=TRUE)}
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> >? ? ???
> > ??? [[alternative HTML version
> deleted]]
> > 
> > 
> > ______________________________________________
> > 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.
> > 
> > 
> 
> -- 
> View this message in context:
http://www.nabble.com/code-that-will-use-two-data-sets-which-differ-in-size.-tp24214485p24239706.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.
> 

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