R equivalent of SELECT DISTINCT on two or more fields/variables

Posted by wahalulu on Stack Overflow See other posts from Stack Overflow or by wahalulu
Published on 2010-05-24T21:38:19Z Indexed on 2010/05/24 21:41 UTC
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Say I have a dataframe df with two or more columns, is there an easy way to use unique() or other R function to create a subset of unique combinations of two or more columns?

I know I can use sqldf() and write an easy "SELECT DISTINCT var1, var2, ... varN" query, but I am looking for an R way of doing this.

It occurred to me to try ftable coerced to a dataframe and use the field names, but I also get the cross tabulations of combinations that don't exist in the dataset:

uniques <- as.data.frame(ftable(df$var1, df$var2))

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R equivalent of SELECT DISTINCT on two or more fields/variables - Developer IT

R equivalent of SELECT DISTINCT on two or more fields/variables

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SQL SERVER – Concat Function in SQL Server – SQL Concatenation

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Nested SQL Select statement fails on SQL Server 2000, ok on SQL Server 2005

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