Hi R Experts,

How do I mark rows in dataframe based on a condition that's based off another row in the same dataframe?

I want to mark any combination of FY,ID, TT=='HC' rows that have a FY,ID,TT=='TER' row with a 1.  In my example below this is rows 4, 7 and 11.
My data looks something like this:
    FY ID  TT
1  FY09  1  HC
2  FY10  1  HC
3  FY11  1  HC
4  FY12  1  HC
5  FY12  1 TER
6  FY09  2  HC
7  FY10  2  HC
8  FY10  2 TER
9  FY11  2  HC
10 FY12  2  HC
11 FY13  2  HC
12 FY13  2 TER

I know for this specific example I can use:
HTDF$EXCL3<-1*duplicated(HTDF[,1:2],fromLast=T)

However my actual data set is NOT sorted by FY, ID and TT. TT is a binary factor variable. I want to know if there is another way of doing the same thing without sorting the data.
I tried the last line of code below but it gave me unexpected results. It marks the first three rows with 0 and everything else with 1.  Based on the warning messages looks like it has something to do with longer object length is not a multiple of shorter object length. But I am now stumped.

#REPRODUCIBLE EXAMPLE
FY<-factor(c("FY09","FY10","FY11","FY12","FY12","FY09","FY10","FY10","FY11","FY12","FY13","FY13"))
ID<-c(rep(1,5),rep(2,7))
TT<-factor(c(rep("HC",4),"TER","HC","HC","TER","HC","HC","HC","TER"))
HTDF<-data.frame(FY,ID,TT)

#Summarize data and get max TT. TT is a binary factor variable
library(sqldf)
HTDF.MAX<-sqldf('SELECT ID,FY,Max(TT) "MAXTT" FROM HTDF GROUP BY ID,FY')

# Initiate new variable and assign 0 or 1
HTDF$EXCL<-0

# THIS IS WHERE I AM GETTING UNEXPECTE RESULTS
HTDF$EXCL<-ifelse(HTDF$FY==HTDF.MAX$FY&HTDF$ID==HTDF.MAX$ID&HTDF$TT==HTDF.MAX$MAXTT,0,1)


Dan Lopez
Workforce Analyst
LLNL
HRIM - Workforce Analytics & Metrics

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