R help - Jun 2008 - Need advise in grab the line number of sorted list in R

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.

	[[alternative HTML version deleted]]

Jason Lee:
> 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'm not sure I understand what you're trying to do. Could you try to
explain
using code example of how you 'grab' elements?

One solution could perhaps be to simple renumber the data frame. If the data
frame is named 'dat', you can do it simply by

row.names(dat) = NULL

-- 
Karl Ove Hufthammer

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