[R] selecting certain rows from data frame

[Peter Ehlers]

On 2010-12-15 09:44, Hrithik R wrote:
> Hi Steven and Peter,
> I apologise for not providing the code for the sample
> I now realise what I need may be a bit tricky...
> my dataframe has hundreds of IDs in which case Steven's solution will
> not be optimum
> Peter's solution seems best, but how do I reverse this and use it to
> select the dataframe rows which */_do not_/* contain particular IDs say
> for example IDs 2 and 5 in this case.

That's easy; use the 'NOT' operator ('!' in R):

  DF2 <- subset(DF, !(ID %in% c(2,5)))

Peter Ehlers

> Thanks again for your time
> Rith
>
> ------------------------------------------------------------------------
> *From:* Peter Ehlers <ehlers at ucalgary.ca>
> *To:* steven mosher <moshersteven at gmail.com>
> *Cc:* Hrithik R <rithrr at yahoo.com>; "r-help at r-project.org"
> <r-help at r-project.org>
> *Sent:* Wed, December 15, 2010 3:26:14 AM
> *Subject:* Re: [R] selecting certain rows from data frame
>
> On 2010-12-14 23:57, steven mosher wrote:
>  > Hi,
>  > Next time give folks code to produce a toy sample of your problem
>  >
>  > DF<-data.frame(ID=rep(1:5,each=3),Data=rnorm(15),Stuff=seq(1:15))
>  > DF
>  > ID Data Stuff
>  > 1 1 2.0628225 1
>  > 2 1 0.6599165 2
>  > 3 1 0.5672595 3
>  > 4 2 -0.5308823 4
>  > 5 2 -0.5358471 5
>  > 6 2 -0.1414992 6
>  > 7 3 -0.1679643 7
>  > 8 3 0.9220922 8
>  > 9 3 0.8863018 9
>  > 10 4 -0.7255916 10
>  > 11 4 -1.2446753 11
>  > 12 4 0.8165567 12
>  > 13 5 0.0925008 13
>  > 14 5 -0.8534803 14
>  > 15 5 -0.6535016 15
>  >
>  > # now I want to select rows where ID = 2 or 5
>  > # Assign DF2 to those elements of DF where the ID variable=2 or 5
>  >
>  > DF2<- DF[which(DF$ID==2 | DF$ID==5), ]
>
> Or use subset():
>
> DF2 <- subset(DF, ID %in% c(2,5))
>
> Peter Ehlers
>
>  > DF2
>  > ID Data Stuff
>  > 4 2 -0.5308823 4
>  > 5 2 -0.5358471 5
>  > 6 2 -0.1414992 6
>  > 13 5 0.0925008 13
>  > 14 5 -0.8534803 14
>  > 15 5 -0.6535016 15
>  >
>  > On Tue, Dec 14, 2010 at 10:10 PM, Hrithik R<rithrr at yahoo.com
> <mailto:rithrr at yahoo.com>> wrote:
>  >
>  >> Hi,
>  >> if I have a dataframe such that
>  >>
>  >> ID Time Earn
>  >> 1 1 10
>  >> 1 2 50
>  >> 1 3 68
>  >> 2 1 40
>  >> 2 2 78
>  >> 2 4 88
>  >> 3 1 50
>  >> 3 2 60
>  >> 3 3 98
>  >> 4 1 33
>  >> 4 2 48
>  >> 4 4 58
>  >> .....
>  >> ....
>  >> .....
>  >>
>  >> Now if I have to select the all the rows from the data frame which
> does not
>  >> include rows with certain IDs, say for example (prime) ID == 2& 3,
> how do
>  >> I do
>  >> it
>  >>
>  >>
>  >> Thanks
>  >>
>  >> Rith
>  >>
>