[R] Subscripting

[David Winsemius]

On Feb 10, 2010, at 2:26 PM, GL wrote:

>
> Dataframe1 contains a list of specific dates. Dataframe2 contains a  
> large
> dataset, one element of which is Date. How do I create a subset of
> Dataframe2 that excludes the dates from Dataframe1? I know how to do  
> it with
> a left outer join vs null in SQL, but I can't figure out how to do  
> it more
> directly via the subcripts that already exist?
>
> Dateframe1
>
> Date
> 1/1/2010
> 1/18/2010
>
>
> Dataframe2
>
> Date Attribute Count
> 1/1/2010 Red 5
> 1/15/2010 Green 2
> 1/18/2010 Purple 8
> 1/19/2010 Yellow 3
>

Something along the lines of this untested code:

  Dataframe2[ !(Dataframe2$Date %in% Dataframe1$Date) , ]

?"["
?"%in%"


> ResultingDataframe (Dataframe2 minus the rows that have Dates in  
> Dataframe1)
>
> Date Attribute Count
> 1/15/2010 Green 2
> 1/19/2010 Yellow 3
>
> -- 
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David Winsemius, MD
Heritage Laboratories
West Hartford, CT