If all you want is to add a row of na's could you just do something
like:
nExpectedRows<-length(unique(animals)) * length(unique(animalYears)) * 2
newDf<-data.frame(animals=rep(NA,nExpectedRows-nrow(comAn)),
animalYears=rep(NA,nExpectedRows-nrow(comAn)),
animalMass=rep(NA,nExpectedRows-nrow(comAn)))
comAn = rbind(comAn,newDf)
On Thu, 2015-03-05 at 13:41 -0700, Curtis Burkhalter wrote:
> Hello everyone,
>
> I'm having a problem with a function that I wrote that is supposed to add a
> row to dataframe based upon a conditional statement. To explain I've used
> an example below:
>
> #create data frame
> animals=c("bird","dog","cat")
> animals=rep(animals,each=4)
> animals=animals[1:11]
> animalYears=c(1,1,2,2,1,1,2,2,1,1,2)
> animalMass=round(runif(11,min=10,max=50),0)
>
> comAn=as.data.frame(cbind(animals,animalYears,animalMass))
> comAn
>
> * animals* *animalYears* *animalMass*
> 1 bird 1 30
> 2 bird 1 32
> 3 bird 2 27
> 4 bird 2 16
> 5 dog 1 22
> 6 dog 1 25
> 7 dog 2 41
> 8 dog 2 22
> 9 cat 1 30
> 10 cat 1 37
> 11 cat 2 49
>
> We can see here that for every type of animal I have two years of mass
> measurements, except for the cat in year 2. What I want to do is add an
> additional row to the end of the dataframe that consists strictly of NAs
> and then I can substitute those out later.
>
> So what I first did was split the 'comAn' dataframe into the different
> Animal by Year combos.
>
> #This line splits 'com_An' into a list ordered by the Animal by Year combos
> comAn_split=split(comAn, paste(comAn$animals,comAn$animalYear))
>
> Then I wrote the function that identifies whether a particular Animal by
> Year combo is less than two rows in length and if so it should add another
> row that consists only of NAs using the vector 'NAs':
>
> #This function identifies the length of each Animal by Year combo and then
> #uses the rbind function built in R to add a row
> #to each animal by year combo if they have less than 2 samples
>
> addNA <- function(comAn) {
> NAs=c(NA,NA,NA)
> ind <- seq_len(nrow(comAn))
> comAn[ifelse(length(ind)<2,rbind(NAs),length(ind)),]
> }
>
> #This applies the function addNs to the animals data organized in list
> format
> addedNAcomAn <- do.call(rbind, lapply(comAn_split, addNA))
> addedNAcomAn
>
> When I apply the function to the list of the different Animal by Year
> combos this is what I get:
> animals animalYears animalMass
> bird 1 bird 1 23
> bird 2 bird 2 50
> cat 1 cat 1 15
> cat 2 <NA> <NA> <NA>
> dog 1 dog 1 23
> dog 2 dog 2 38
>
> What I expect is this:
>
> animals animalYears animalMass
> 1 bird 1 41
> 2 bird 1 23
> 3 bird 2 23
> 4 bird 2 50
> 5 dog 1 49
> 6 dog 1 23
> 7 dog 2 13
> 8 dog 2 38
> 9 cat 1 42
> 10 cat 1 15
> 11 cat 2 33
> 12 NA NA NA
>
> Am I conditioning improperly within the function or am I missing something
> else. Any help would be greatly appreciated.
>
> Best
>
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