[R] Re moving rows which do not satisfy a condition

[David Winsemius]

Bill Dunlap sent me a couple of more compact versions and perhaps  
forgot the hit "reply all":

  Data[ Data[,1]^2 + Data[,2]^2 >= 49, , drop=FALSE]

And a second one that handles higher dimensions than 2, still with and  
L2 metric:

  Data[ rowSums(Data^2)>49, , drop=FALSE]

-- 
David Winsemius

On Nov 23, 2009, at 6:13 PM, David Winsemius wrote:

>
> On Nov 23, 2009, at 2:57 PM, sandsky wrote:
>
>>
>> Hello,
>>
>> Considering 5 points in X-Y plain. Data is a 5*2 matrix (5 rows for  
>> samples
>> & 2 columns for X and Y)
>> With a distance from the origin, if a distance < 7, remove the row  
>> from the
>> Data.
>>
>> After calculating the distance for each point, I can't forward  
>> because of
>> this "Removing" problem.
>>
>> Anyone can help me?
>>
>>
>> Data=matrix(1:10,5,2)
>
> > Data[apply(Data, 1, function(x) sqrt(x[1]^2+x[2]^2)>=7), ]
>     [,1] [,2]
> [1,]    2    7
> [2,]    3    8
> [3,]    4    9
> [4,]    5   10
>
>>
>> a=rep(0,5);
>> b=rep(0,5);
>>
>> for (i in 1:5))
>> {
>>    for (k in 1:2)
>>    {	
>>       a[i,k]=a[i,k]+(Data[i,k])^2
>>    }
>>    b[i,j]=(a[i,j])^0.5   # distance from the origin
>> }	
>>
>>
>> Thank you,
>>
>> Jin
>> 	
>>
>>
>> -- 
>> View this message in context: http://old.nabble.com/Removing-rows-which-do-not-satisfy-a-condition-tp26484778p26484778.html
>> Sent from the R help mailing list archive at Nabble.com.
>>
>> ______________________________________________
>> 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.
>
> David Winsemius, MD
> Heritage Laboratories
> West Hartford, CT
>
> ______________________________________________
> 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.

David Winsemius, MD
Heritage Laboratories
West Hartford, CT