CODEWITHSUNDEEP
rduplicates
April
April

Reputation: 21

Count the number of Occurences of duplicates R Code

I need a line of code that will search a vector of numbers and return the number of occurrences. For Example

a=c(15,32,27, 63, 15,99, 32,32)

dup=unique(a[duplicated(V.Ints)])
len=length(unique(duplicated(dup)))

I get:

> dup
#[1] 15, 32

> len
#[1] 2

but what I need is:

> dup
#[1] 15, 32

> len
#[1] 5

Thank you!

Upvotes: 2

Views: 154

Answers (3)

Steven Beaupré
Steven Beaupré

Reputation: 21641

Arun's suggestion in the comments is the way to go:

> sum(a %in% c(15,32))
#[1] 5

For more general usage:

sum(a %in% unique(a[duplicated(a)]))

Or a one-liner in the spirit of Mr Flick's approach:

sum(a %in% names(which(table(a) > 1)))

Upvotes: 3

Rich Scriven
Rich Scriven

Reputation: 99371

Another variation is to grab all the duplicated values then use length() for len and unique() for dup

x <- a[duplicated(a) | duplicated(a, fromLast=TRUE)]

length(x)
# [1] 5
unique(x)
# [1] 15 32

Upvotes: 2

MrFlick
MrFlick

Reputation: 206566

You can count frequencies with 

table(a)
# a
# 15 27 32 63 99 
#  2  1  3  1  1

You can filter to find only the duplicates

Filter(function(x) x>1, table(a))
# a
# 15 32 
#  2  3 
names(Filter(function(x) x>1, table(a)))
# [1] "15" "32"

and you can take the sum to find the total length of duplicates

sum(Filter(function(x) x>1, table(a)))
# [1] 5

Upvotes: 2

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