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I have a table with columns A and B and I want to list down all unique elements in column B related to each unique element in column A in R.

Ronak Shah
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Akshit
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    `aggregate(B~A, df, function(x) toString(unique(x)))` – Ronak Shah Aug 29 '19 at 07:49
  • Thanks for the prompt response. I ran it however, it has been almost 2 hrs now and my code hasn't finished executing. Is this normal given that I have some 2,50,00,000 rows? – Akshit Aug 29 '19 at 10:19

1 Answers1

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You probably want to use the function aggregate

Assuming the dataframe/datatable has the name df, you can use the code below:

aggregate(B~A, df, function(x) toString(unique(x)))
txemsukr
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  • Thanks for the prompt response. I ran it however, it has been almost 2 hrs now and my code hasn't finished executing. Is this normal given that I have some 2,50,00,000 rows? – Akshit Aug 29 '19 at 10:19
  • If you have 2 billion rows, it's not surprising that it takes a lot of time. – txemsukr Aug 30 '19 at 07:36