[R] Subset and 0 replace?

[Vin Cheng]

Hi,
 
I'm trying to group rows in a dataframe with SPCLORatingValue factor >16 and summing the Wgt's that correspond to this condition.  There are 100 dataframes in a list.  
 
Some of the dataframes won't have any rows that have this condition SPCLORatingValue>16 and therefore no corresponding weight.  
 
My problem is that I need to have a corresponding value for each dataframe in the list - so 100 values. 
 
If dataframe 44 doesn't have any SPCLORatingValue>16, then I end up getting a vector that's 99 long vs. 100.  putting value 45 into 44's slot and so on.
 
Is there either an if/else statement or argument I can place into subset to put a 0 for the data frames that don't have SPCLORatingValue>16?
 
GenEval[18,1:100] <- t(summaryBy(Wgt.sum~as.numeric(.id),data=subset(ldply(Generation,function(x) summaryBy(Wgt ~ SPCLORatingValue, data=x, FUN=c(sum))),SPCLORatingValue>16),FUN=c(sum),order=FALSE))
 
Any help or guidance would be greatly appreciated!
Many Thanks,
Vince
 
 
 		 	   		  
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