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Consider a dataframe like the following:

Key | Value
A   | 1
A   | 2
B   | 2
C   | 3

I want to filter this dataframe based on the condition that only get rows with the key where the key occurs more than once.

So the expected output is 

Key | Value
A   | 1
A   | 2

What's the most succinct way of doing this in R? Looking for a generalized solution where count the count can be > n

Ankit Dhingra
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2 Answers2

3

We can use

library(dplyr)
df1 %>%
    group_by(Key) %>%
    filter(n()>1)

Or with base R using table and subset

subset(df1, Key %in% names(which(table(Key) > 1)))
akrun
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1

Using data.table 

df <- data.table(read.table(text = "Key  Value
A   1
A   2
B   2
C   3", header = T))

df[, if(.N > 1) .SD, by = Key ]

   Key Value
1:   A     1
2:   A     2
Hardik Gupta
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