[R] selecting certain rows from data frame

[David Winsemius]

On Dec 15, 2010, at 4:18 AM, Ivan Calandra wrote:

> Hi,
>
> Just to note that which() is unnecessary here:
> DF2 <- DF[DF$ID==2 | DF$ID==5, ]

And to further note that it is only unnecessary of you have no NA's in  
that ID column.

 > DF[4,1] <- NA
 > DF[8,1] <- NA
 > DF2 <- DF[DF$ID==2 | DF$ID==5, ]

(These NA rows would not appear if which() were used.)

-- 
David.
>
> Ivan
>
> Le 12/15/2010 08:57, steven mosher a écrit :
>> 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), ]
>>  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>  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
>>>
>>>
>>>
>>>        [[alternative HTML version deleted]]
>>>
>>>
>>> ______________________________________________
>>> R-help at r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>> PLEASE do read the posting guide
>>> http://www.R-project.org/posting-guide.html
>>> and provide commented, minimal, self-contained, reproducible code.
>>>
>>>
>> 	[[alternative HTML version deleted]]
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
> -- 
> Ivan CALANDRA
> PhD Student
> University of Hamburg
> Biozentrum Grindel und Zoologisches Museum
> Abt. Säugetiere
> Martin-Luther-King-Platz 3
> D-20146 Hamburg, GERMANY
> +49(0)40 42838 6231
> ivan.calandra at uni-hamburg.de
>
> **********
> http://www.for771.uni-bonn.de
> http://webapp5.rrz.uni-hamburg.de/mammals/eng/1525_8_1.php
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.