How do I merge two tables by ID number, but only keeping data where there is duplicate IDs?

Question

I am using R. I have two tables, both with an ID variable. I want to make another table where I have a column for ID which only has IDs that appear in both original tables, plus a column for another variable that only appeared in one of the original tables.

Any help would be much appreciated.

This is a very common question, the default settings of the base R `merge` function will work fine. Have a look at the help page: `?merge`. In the future, please provide a [reproducible example](https://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example-aka-mcve-minimal-complete-and-ver), but first spend some time searching for similar questions. — lmo, Nov 28 '17 at 12:37

score 1 · Answer 1 · answered Nov 28 '17 at 12:36

1

Try this

library(dplyr)
df_temp <- inner_join(df_1, df_2, by=ID)
df_3 <- subset(df_temp, select = c(ID, OtherColumn))

answered Nov 28 '17 at 12:36

Barbara

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Perfect thank you so much!! – amelia28 Nov 28 '17 at 12:50

How do I merge two tables by ID number, but only keeping data where there is duplicate IDs?

1 Answers1