How to find the index of values in an R data frame column if they occur once?

To find the index of values in an R data frame column if they occur once, we can follow the below steps −

• First of all, create a data frame.

• Then, use which function along with duplicated function and single square brackets for subsetting to find the index of values in a column if they occur once.

Example

Create the data frame

Let’s create a data frame as shown below −

x<-sample(1:10,25,replace=TRUE) df1<-data.frame(x) df1

Output

On executing, the above script generates the below output(this output will vary on your system due to randomization) −

 x 1 5 2 3 3 10 4 1 5 9 6 8 7 8 8 7 9 4 10 6 11 1 12 6 13 5 14 5 15 7 16 5 17 1 18 2 19 1 20 3 21 7 22 7 23 9 24 10 25 1

Find the index of values in a column if they occur once

Using which function along with duplicated function and single square brackets for subsetting to find the index of values in column x of data frame df1 if they occur once −

x<-sample(1:10,25,replace=TRUE) df1<-data.frame(x) which(!(df1$x %in% df1$x[duplicated(df1$x)]))

Output

[1] 9 18 

Example 2

Create the data frame

Let’s create a data frame as shown below −

y<-round(rnorm(25),1) df2<-data.frame(y) df2

Output

On executing, the above script generates the below output(this output will vary on your system due to randomization) −

     y 1   2.1 2  -1.0 3  -1.6 4   1.5 5   0.5 6   1.4 7   0.2 8   0.6 9 0.2 10  0.6 11  0.4 12  0.2 13  0.4 14  1.6 15  1.4 16 -1.6 17 -1.1 18  0.4 19  1.0 20  0.3 21  0.4 22 -0.7 23 -0.9 24 -1.6 25 -0.4

Find the index of values in a column if they occur once

Using which function along with duplicated function and single square brackets for subsetting to find the index of values in column y of data frame df2 if they occur once −

y<-round(rnorm(25),1) df2<-data.frame(y) which(!(df2$y %in% df2$y[duplicated(df2$y)]))

Output

[1] 1 2 4 5 14 17 19 20 22 23 25