[R] Select top three values from data frame
ottorino-luca.pantani at unifi.it
Wed Aug 26 11:46:27 CEST 2009
df.mydata[df.mydata$A=="X" AND df.mydata$C < 2, ]
will do the job ?
Noah Silverman ha scritto:
> 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?
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