check.nodup.RdFunction that checks if a variable has no duplicated values for each subject.
check.nodup(x, id, data, out=1, na.rm=TRUE)
| x | argument to specify the variable to check. |
|---|---|
| id | argument to specify a subject id variable. |
| data | optional data frame that contains the variables specified above. |
| out | either a string or an integer ( |
| na.rm | logical indicating whether missing values should be removed before checking (default is |
The function checks if a variable has no duplicated values for each subject.
When na.rm=TRUE (the default), missing values are ignored. When setting na.rm=FALSE, then missing values are treated as distinct values from any non-missing values. See ‘Examples’.
When out = 1 or out = "logical", the function simply returns a logical (i.e., TRUE or FALSE), depending on whether the variable has no duplicated values within each subject.
When out = 2 or out = "id", the function returns a vector with the ids of those subjects where the variable has duplicated values.
When out = 3 or out = "data", the function returns the data for those subjects where the variable has duplicated values.
Wolfgang Viechtbauer wvb@wvbauer.com
# illustrative dataset dat <- data.frame(subj=rep(1:4, each=5), obs = 1:5, age = rep(c(20,31,27,22), each=5), stress = c(2,3,1,4,2, 3,3,3,3,3, 1,1,2,6,4, 1,2,1,3,1)) dat#> subj obs age stress #> 1 1 1 20 2 #> 2 1 2 20 3 #> 3 1 3 20 1 #> 4 1 4 20 4 #> 5 1 5 20 2 #> 6 2 1 31 3 #> 7 2 2 31 3 #> 8 2 3 31 3 #> 9 2 4 31 3 #> 10 2 5 31 3 #> 11 3 1 27 1 #> 12 3 2 27 1 #> 13 3 3 27 2 #> 14 3 4 27 6 #> 15 3 5 27 4 #> 16 4 1 22 1 #> 17 4 2 22 2 #> 18 4 3 22 1 #> 19 4 4 22 3 #> 20 4 5 22 1# check that variable obs has no duplicated values within subjects check.nodup(obs, subj, data=dat)#> [1] TRUE# introduce a duplicated value for the third subject dat$obs[13] <- 2 # check that variable obs has no duplicated values within subjects check.nodup(obs, subj, data=dat)#> [1] FALSE# for which subjects are there duplicated values? check.nodup(obs, subj, data=dat, out=2)#> [1] "3"# show the data for those subjects check.nodup(obs, subj, data=dat, out=3)#> subj obs age stress #> 11 3 1 27 1 #> 12 3 2 27 1 #> 13 3 2 27 2 #> 14 3 4 27 6 #> 15 3 5 27 4