Re: [R] Need advise in grab the line number of sorted list in R

From: Marc Schwartz <marc_schwartz_at_comcast.net>
Date: Mon, 02 Jun 2008 09:02:23 -0500

on 06/02/2008 08:45 AM Jason Lee wrote:
> Hi,
>
> I have a data frame which format is like below:-
>
> X Y Z
> 131 22.2 3.4 4.4
> 150 20.0 12.2 4.5
>
> etc...
>
> And I have sorted the data frame. However, I would like to grab one of these
> elements in the data frame. Also, i would like to number these rows so that
> when i grab a particular line let say 150, it is able to return me the
> position of the row rather than the "150". Let say in this example, when i
> grab a value of 150, it gives me 2 rather than 150.
>
>
> I tried to add anohter extra column of number which is data$NUMBER =
> row.names(data) on the sorted data but it seems not giving what I wanted
> which is the "position" of the row 150.
>
> Please advise. Thanks.

Is this what you want?

 > DF

        X Y Z
131 22.2 3.4 4.4
150 20.0 12.2 4.5

 > which(row.names(DF) == 150)
[1] 2

See ?which

HTH, Marc Schwartz



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