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How to find the number of unique values in a vector by excluding missing values in R?
If there exist missing values in an R vector then it is counted as a unique value in the vector, therefore the extraction of unique values cannot be done directly. For this purpose, we need to use unique with na.omit function. For example. If we have a vector called x with missing values then the extraction of unique values can be done as length(unique(na.omit(x))).
Example1
x1<−sample(c(NA,rpois(5,1)),200,replace=TRUE) x1
Output
[1] 0 0 1 1 1 NA NA 0 1 1 0 NA 1 0 0 NA 0 0 NA 1 0 0 0 1 1 [26] 0 0 0 0 0 NA 1 0 1 NA 1 0 1 1 1 1 1 1 0 1 1 0 0 0 0 [51] 1 NA 1 0 0 NA NA 0 0 0 1 NA 0 0 1 NA 1 1 0 1 NA 0 0 1 NA [76] 1 NA 1 0 NA 1 NA 0 0 1 0 0 NA 1 0 1 0 1 0 1 1 0 0 0 0 [101] 0 0 1 1 0 1 0 NA 0 NA 0 0 0 1 0 0 0 0 NA NA NA 0 1 0 0 [126] 1 0 1 0 0 0 0 1 0 1 0 0 NA 1 1 1 0 0 0 0 1 1 0 NA 0 [151] 0 NA 1 0 0 0 1 1 0 NA 1 1 0 0 1 0 0 NA 0 0 1 0 0 0 1 [176] 1 1 0 NA NA 0 1 1 NA 0 NA 0 1 1 0 0 1 0 1 0 NA 1 1 1 0
Example
length(unique(na.omit(x1)))
Output
[1] 2
Example2
x2<−sample(c(NA,0,1,2),200,replace=TRUE) x2
Output
[1] NA 0 0 NA 0 0 0 NA 2 1 2 0 0 NA 2 1 1 0 NA 2 2 NA 2 NA 1 [26] 1 2 1 1 1 2 0 2 0 0 0 1 NA NA 1 1 2 1 0 1 0 NA 0 0 1 [51] NA NA 0 0 0 0 NA 2 0 NA 0 2 0 NA 0 NA NA 2 0 0 0 NA 2 NA 1 [76] NA 2 0 1 2 0 2 NA 2 NA NA 1 1 0 NA 2 NA 0 0 NA NA 0 NA 1 NA [101] 2 2 2 1 NA 1 1 2 0 1 2 2 2 2 1 0 2 NA 1 NA 1 1 NA 0 NA [126] 0 NA 1 NA 2 NA 1 NA NA 2 NA 2 0 1 2 1 0 1 1 0 NA NA 1 0 1 [151] NA 0 0 2 NA NA 2 NA NA 1 NA 2 0 NA 1 NA 0 NA 0 0 2 1 0 NA 2 [176] 1 0 2 1 1 1 0 0 0 NA NA NA 0 0 NA 1 0 NA NA NA NA 1 NA 0 2
Example
length(unique(na.omit(x2)))
Output
[1] 3
Example3
x3<−sample(c(NA,0:9),200,replace=TRUE) x3
Output
[1] NA NA 8 4 1 8 8 4 0 6 5 1 8 2 7 2 2 1 7 8 3 9 0 8 9 [26] 6 4 5 NA NA 2 1 1 3 1 8 6 7 1 5 9 5 8 9 1 5 5 3 1 2 [51] NA 6 3 9 NA 4 3 NA NA 9 4 NA 8 6 1 7 3 9 3 4 5 1 8 6 1 [76] 9 7 4 8 7 9 7 1 9 NA 5 6 8 NA 6 8 6 9 8 6 0 8 9 1 1 [101] 0 4 7 6 4 8 2 5 2 7 9 4 3 8 3 7 2 2 6 6 NA 0 8 2 4 [126] 2 6 NA NA 2 5 2 7 6 8 4 7 7 7 5 0 8 1 4 2 5 9 8 4 4 [151] 9 1 3 9 3 1 6 8 7 6 3 0 2 NA 6 1 0 2 3 0 2 NA 9 0 2 [176] 8 5 5 0 2 5 8 4 6 3 9 0 2 7 8 4 4 NA 5 8 NA NA NA 4 0
Example
length(unique(na.omit(x3)))
Output
[1] 10
Example4
x4<−sample(c(NA,1:10),200,replace=TRUE) x4
Output
[1] 1 NA NA 5 8 10 1 2 9 1 8 9 4 9 2 6 1 NA 9 5 8 3 4 10 7 [26] 5 5 6 2 4 8 7 9 2 7 3 8 10 7 8 3 5 5 7 6 4 4 7 5 7 [51] 9 8 5 6 6 4 5 5 5 2 10 7 7 NA 3 5 5 1 5 1 2 2 4 9 7 [76] 1 3 8 7 NA 10 2 4 7 10 6 6 7 4 10 3 10 3 2 4 NA 7 10 8 7 [101] 10 10 6 1 NA 9 1 6 NA 4 1 5 10 10 6 NA 10 NA 2 5 2 5 2 10 10 [126] 6 7 4 2 4 7 6 10 4 5 10 1 5 4 8 6 6 6 1 10 10 8 7 2 NA [151] 3 9 5 1 10 1 4 5 8 7 4 2 10 10 6 5 8 NA 8 6 9 4 2 NA NA [176] NA 7 NA 1 1 5 8 8 5 9 2 NA 2 2 8 2 4 4 6 4 9 10 8 3 NA
Example
length(unique(na.omit(x4)))
Output
[1] 10
Example5
x5<−sample(c(NA,5,10,15,20,25),200,replace=TRUE) x5
Output
[1] 5 5 15 5 15 10 15 15 20 15 5 10 25 5 NA NA 20 25 10 NA NA 20 10 10 15 [26] 10 NA 25 10 25 5 15 NA 15 NA 15 15 5 10 5 5 NA 15 NA 10 5 10 NA NA NA [51] 25 5 10 NA 10 10 15 20 20 5 25 20 20 20 25 20 15 NA 10 5 15 15 10 5 5 [76] 5 NA 25 5 10 20 NA 25 10 20 20 NA NA 10 5 25 25 20 25 15 10 NA 25 5 15 [101] 25 NA 25 NA 5 NA 10 5 25 25 NA 15 20 5 20 5 15 15 NA 25 25 5 20 25 NA [126] 25 20 5 25 5 15 25 10 15 NA 10 NA 15 25 15 25 NA NA 15 25 NA 25 25 NA 20 [151] NA NA 20 5 25 20 15 25 10 20 5 10 NA 25 25 NA 5 15 25 20 10 15 NA 5 5 [176] 10 NA 5 10 10 5 25 NA 5 5 10 10 5 20 10 20 NA 25 5 5 10 25 20 25 20
Output
length(unique(na.omit(x5)))
Output
[1] 5
Example6
x6<−sample(c(NA,rnorm(5)),80,replace=TRUE) x6
Output
[1] −2.4891929 −2.4891929 −0.1627979 −1.8763364 −0.6250307 NA [7] −0.1627979 NA −0.1627979 NA −0.6250307 −0.6250307 [13] −2.4891929 −0.1627979 −2.4891929 NA NA −2.4891929 [19] −2.4891929 −0.1627979 −2.4891929 −0.6250307 −1.8763364 −1.8763364 [25] −1.8763364 −2.4891929 −2.4891929 −2.4891929 −2.4891929 −1.8763364 [31] −2.4891929 NA −0.6250307 NA −1.8763364 −0.1627979 [37] −2.4891929 −0.6250307 −2.4891929 −0.6250307 −1.8763364 −1.8763364 [43] NA −2.4891929 −0.6250307 −0.6250307 −0.6250307 −0.6250307 [49] −0.1627979 −0.6250307 −0.6250307 −2.4891929 −1.8763364 NA [55] −2.4891929 −0.1627979 −0.2147164 −1.8763364 −2.4891929 −1.8763364 [61] −0.2147164 −1.8763364 −2.4891929 −0.6250307 −0.6250307 −0.6250307 [67] −0.1627979 −0.6250307 −2.4891929 −2.4891929 −0.6250307 −0.2147164 [73] −2.4891929 −0.1627979 −0.1627979 −0.2147164 −0.2147164 −0.6250307 [79] −2.4891929 −0.6250307
Example
length(unique(na.omit(x6)))
Output
[1] 5
Updated on: 09-Feb-2021
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