R help - Jul 2011 - applying a loop to multiple dataframes

Hello again R-folks,
I'm trying to apply a loop to multiple data frames and then organize the
data in a manageable form. I have the code for my loop figured out (thanks to
help from this list)...it runs up to 2000 iterations of a "while" loop
until it finds a 40-row "d2p" column sum >5

n<-nrow(dsub.f1)
test<-0
for(k in 1:2001){
	if(k>2000){
	break}  #stops after 2000 iterations
	else{
	while(test<5){  #continues unti sum>5, or 2000 iter.
	i<-sample(1:n-40,1)
	x<-dsub.f1[seq(from=i, to=i+40),]
	test<-sum(x[,"d2p"],na.rm=TRUE)}
	}
	}
 
My data frames are all named dsub.f1 through dsub.f360 (and are subsets of a
laster data frame "d") which I created using this code:

for(i in 1:360){
assign(paste("dsub.f",d[d$fish==i,1],sep=""),subset(d[d$fish==i,]))}


I created a list of all my data frames using:

df.filter<-function(x) inherits(get(x),'data.frame')
		 #pulls all dataframes 
dfs<-Filter(df.filter,ls());str(dfs) 
dsubs<-dfs[3:360];head(dsubs) 
		#removes "d" and "data.csv" dataframes that I don't
want

But I can't figure out how to write a "for" loop that will apply
the (top) code above to each data frame.

Also, once I'm able to apply the loop to each data frame, I would like to
organize the data in a manageable form so I can reference it in other analyses.

I hope I explained what I'm trying to do well enough. Thanks!!!

sean







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On 22.07.2011 22:42, Sean Bignami wrote:
> Hello again R-folks,
> I'm trying to apply a loop to multiple data frames and then organize
the data in a manageable form. I have the code for my loop figured out (thanks
to help from this list)...it runs up to 2000 iterations of a "while"
loop until it finds a 40-row "d2p" column sum>5
>
> n<-nrow(dsub.f1)
> test<-0
> for(k in 1:2001){
> 	if(k>2000){
> 	break}  #stops after 2000 iterations
> 	else{
> 	while(test<5){  #continues unti sum>5, or 2000 iter.
> 	i<-sample(1:n-40,1)
> 	x<-dsub.f1[seq(from=i, to=i+40),]
> 	test<-sum(x[,"d2p"],na.rm=TRUE)}
> 	}
> 	}
>
I don't see much sense in the code above. Which of the objects are you 
interested in?


> My data frames are all named dsub.f1 through dsub.f360 (and are subsets of
a laster data frame "d") which I created using this code:
>
> for(i in 1:360){
>
assign(paste("dsub.f",d[d$fish==i,1],sep=""),subset(d[d$fish==i,]))}

I find it easier to put such things in a list as in:

dsub.f <- split(d, d$fish)

>
> I created a list of all my data frames using:
>
> df.filter<-function(x) inherits(get(x),'data.frame')
> 		 #pulls all dataframes
> dfs<-Filter(df.filter,ls());str(dfs)
> dsubs<-dfs[3:360];head(dsubs)
> 		#removes "d" and "data.csv" dataframes that I
don't want

This is not required since those data.frames are collected in one list 
(see above).


> But I can't figure out how to write a "for" loop that will
apply the (top) code above to each data frame.

Just write the code in a function athat assumes a data.frame as an 
argument and then sapply() it on your list of data.frames.

Best wishes,
Uwe Ligges



> Also, once I'm able to apply the loop to each data frame, I would like
to organize the data in a manageable form so I can reference it in other
analyses.
>
> I hope I explained what I'm trying to do well enough. Thanks!!!
>
> sean
>
>
>
>
>
>
>
> 	[[alternative HTML version deleted]]
>
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