[R] "Delete row" takes ages. alternative?!

[David Winsemius]

On Jul 9, 2011, at 7:02 PM, sven wrote:

> Hello,
> I am a student from Liverpool UK, working with some genetic data  
> using R.
>
> I got a data.frame with about 250.000 rows and using a for loop to  
> delete
> certain rows using the following code:
>
> x <----- is a data.frame
> x = x[-5,] ---> deletes row 5
> x = x[-10,] ---> delets row 10
> x = x[-i,]   --> deletes row i
> etc...
>
> This takes ages for some reason. Isnt there a quicker way to do this?!

Two ways that would avoid repeated copying of medium size dataframes:

x <- x[-c(5,10, i) , ]

drpidx <- -c(5,10, i)
x <- x[-i, ]

-- 
David.
> Cheers,
> Sven
>
>
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David Winsemius, MD
West Hartford, CT