The function duplicated() returns a logical vector indicating
which elements of x are duplicates, but it does not flag the first
occurrence of subsequently duplicated elements.
Details
allDuplicated returns a logical vector indicating all elements of
x that are involved in ties (i.e., have frequency > 1).
Note that allDuplicated flags all occurrences of tied values, not only
the duplicates beyond the first occurrence.
Consequently, !allDuplicated(x) can be used to identify elements of
x that appear exactly once.
Missing values are considered equal to each other, so multiple NAs
are flagged as ties. As the function builds on duplicated(),
it also works for data frames (row-wise) and matrices.
See also
duplicated() for identifying duplicate elements (excluding first
occurrences). unique() for extracting unique values. split() for grouping tied values. table() for counting frequencies.
Other data.equal:
allIdentical(),
compareDataFrames()
Examples
x <- c(1:10, 4:6)
allDuplicated(x)
#> [1] FALSE FALSE FALSE TRUE TRUE TRUE FALSE FALSE FALSE FALSE TRUE TRUE
#> [13] TRUE
# Compare with duplicated():
duplicated(x)
#> [1] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE TRUE TRUE
#> [13] TRUE
# Elements appearing exactly once
x[!allDuplicated(x)]
#> [1] 1 2 3 7 8 9 10
# Identify and analyse ties
x <- sample(letters[1:10], 20, replace = TRUE)
ties <- split(x, x)
# Number of tied groups
sum(sapply(ties, length) > 1)
#> [1] 6
# Sizes of tied groups
sizes <- sapply(ties, length)
sizes[sizes > 1]
#> b d e f g i
#> 3 2 5 4 2 2
# Same via table()
tab <- table(x)
tab[tab > 1]
#> x
#> b d e f g i
#> 3 2 5 4 2 2