[R] How to align group based on the common values of two columnsinr

[Gerrit Eichner]

Hi, Tammy,

maybe you find something interesting looking at

?interaction

and/or try (with df being your data frame)

df$Group <- as.integer( with( df, interaction( Feature, OS)[, drop = 
TRUE]))

  HtH  --  Gerrit

On Tue, 22 Jan 2013, Tammy Ma wrote:

>
> HI,
>
> I met this problem:
>
> I have the feature data frame:
>
>
>   Feature     OS
>     4              2
>     4              1
>     4              3
>     1              2
>     4              1
>
>
> what I want to do is to autimatically create one more column called "group":
>
>   Feature     OS      Group
>     4              2         1
>     4              1         2
>     4              3         3
>     1              2         4
>     4              1         2
>
>
>
> I don't want "Ifelse", because I have so many combination of feature and OS, I even can not account.  I just want to have sth to autimatically create group indicator based on the difference combination of feature and OS.
>
> Thanks for your help.
>
>
> Kind regards,
> Tammy
>
>
>
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>
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