[R] Select top three values from data frame

[Ottorino-Luca Pantani]

df.mydata[df.mydata$A=="X" AND df.mydata$C < 2, ]
will do the job ?

8rino

Noah Silverman ha scritto:
> Hi,
>
> I'm trying to find an easy way to do this.
>
> I want to select the top three values of a specific column in a subset 
> of rows in a data.frame.  I'll demonstrate.
>
> A    B    C
> x    2    1
> x    4    1
> x    3    2
> y    1    5
> y    2    6
> y    3    8
>
>
> I want the top 3 values of B from the data.frame where A=X and C <2
>
> I could extract all the rows where C<2, then sort by B, then take the 
> first 3.  But that seems like the wrong way around, and it also will 
> get messy with real data of over 100 columns.
>
> Any suggestions?
>