R: How many element of list 1 are in list 2
===

I would like to compare two lists (two rows of a data frame) and count how many differences I have between the two lists.

for instance:

    list1=a,b,c,a
    list2=a,a,d,d

two elements of list 1 are in list 2

I am able to do that with a loop and sum but it is very inefficient. Is there any function to do that in R?

I have checked setdiff and the compare package but did not find anything that helps.

Thanks for your ideas,

Vincent

My function looks like:

    		NRebalancing=function(NamePresent)
			{
			  Nbexchange=NamePresent[,2]
			  Nbexchange=NamePresent[1,2]=0
			  
			  for (i in 2:nrow(NamePresent))
			  {
				print(i)
				compteur=0
				NameNeeded=NamePresent[i,]
				NameNeeded=unique(NameNeeded)
				NameNeeded=na.omit(NameNeeded)
				for(j in 2:length(NameNeeded))
				  #j=1 correspond a une date
				{
				  compteur = compteur+(abs(sum(NamePresent[i,]==as.character(NameNeeded[j]))-sum(NamePresent[i-1,]==as.character(NameNeeded[j]))))
				}
			  Nbexchange[i]=compteur  
			  }
			  
			  return(Nbexchange)
			}