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How to find the number of unique values in each row of an R data frame?
To find the number of unique values in each row of an R data frame, we can use apply function with length and unique function. For example, if we have a data frame called df that contains multiple columns then the number of unique values in each row of df can be found by using the command apply(df,1,function(x) length(unique(x))).
Example1
Consider the below data frame −
> x1<-rpois(20,2) > x2<-rpois(20,2) > x3<-rpois(20,2) > x4<-rpois(20,2) > df1<-data.frame(x1,x2,x3,x4) > df1
Output
x1 x2 x3 x4 1 3 1 1 2 2 3 2 0 2 3 3 2 0 1 4 3 0 3 1 5 3 1 1 2 6 4 4 2 4 7 1 0 2 1 8 0 4 1 2 9 1 4 4 4 10 2 1 2 4 11 1 4 1 2 12 2 5 0 3 13 1 0 3 0 14 2 1 2 2 15 1 0 6 3 16 1 0 5 2 17 3 1 0 3 18 1 3 7 4 19 2 0 1 3 20 1 4 3 0
Finding the number of unique values in each row of df1 −
> apply(df1,1,function(x) length(unique(x))) [1] 3 3 4 3 3 2 3 4 2 3 3 4 3 2 4 4 3 4 4 4
Example2
> y1<-rpois(20,1) > y2<-rpois(20,1) > y3<-rpois(20,1) > y4<-rpois(20,1) > y5<-rpois(20,1) > df2<-data.frame(y1,y2,y3,y4,y5) > df2
Output
y1 y2 y3 y4 y5 1 2 0 0 0 1 2 0 1 0 1 3 3 1 1 1 1 1 4 4 1 1 1 0 5 3 0 0 0 0 6 0 0 0 1 1 7 0 0 3 0 0 8 1 2 3 1 1 9 1 1 3 0 1 10 2 1 1 1 1 11 0 2 0 2 1 12 2 0 1 0 1 13 0 2 0 0 1 14 0 0 1 3 0 15 1 1 2 1 0 16 1 2 2 2 1 17 0 0 0 1 1 18 0 2 0 0 1 19 1 1 0 1 2 20 2 2 0 2 2
Finding the number of unique values in each row of df2 −
> apply(df2,1,function(x) length(unique(x)))
Output
[1] 3 3 1 3 2 2 2 3 3 2 3 3 3 3 3 2 2 3 3 2
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