R: Checking if a set of variables forms a unique index

Question

I have a large dataframe and I want to check whether the values a set of (factor) variables uniquely identifies each row of the data or not.

My current strategy is t

Answer 1

How about:

length(unique(paste(dfTemp$var1, dfTemp$var2, dfTemp$var3)))==nrow(dfTemp)

Paste variables into one string, get unique, and compare the length of this vector with number of rows in your dataframe.