R help - Oct 2013 - How to view un-sampled data from a randomly sampled dataset

Hi there-

I have a 150 row dataset (data). I create "y" a randomly sampled
(without
replacement) set number of observations (40):

y<-data[sample(1:nrow(data),40,replace=FALSE),]

I would like to make a new variable "x" that contains the leftover
non-sampled 110 observations.  I am sure there is a fairly easy way to do
this.

Any help would be greatly appreciated.

THANKS! 



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HI,
You may try:
set.seed(432)
?dat1 <- data.frame(Col1=1:150,Col2=rnorm(150))
?y <- dat1[sample(1:nrow(dat1),40,replace=FALSE),]
x <- dat1[-as.numeric(row.names(y)),]
?dim(x)
#[1] 110?? 2
intersect(row.names(x),row.names(y))
#character(0)

#or
?x1 <- dat1[!row.names(dat1) %in% row.names(y),]
?identical(x,x1)
#[1] TRUE



A.K.



Hi there- 

I have a 150 row dataset (data). I create "y" a randomly sampled
(without replacement) set number of observations (40):

y<-data[sample(1:nrow(data),40,replace=FALSE),] 

I would like to make a new variable "x" that contains the 
leftover non-sampled 110 observations. ?I am sure there is a fairly easy
 way to do this. 

Any help would be greatly appreciated. 

THANKS!

On Oct 23, 2013, at 20:13 , erinu wrote:
> Hi there-
> 
> I have a 150 row dataset (data). I create "y" a randomly sampled
(without
> replacement) set number of observations (40):
> 
> y<-data[sample(1:nrow(data),40,replace=FALSE),]
> 
> I would like to make a new variable "x" that contains the
leftover
> non-sampled 110 observations.  I am sure there is a fairly easy way to do
> this.
> 
> Any help would be greatly appreciated.
> 
> THANKS! 
> 
Just hold on to the indices:

s <- sample(1:nrow(data), 40, replace=FALSE)
y <- data[s,]
x <- data[-s,]

-pd

> 
> 
> --
> View this message in context:
http://r.789695.n4.nabble.com/How-to-view-un-sampled-data-from-a-randomly-sampled-dataset-tp4678887.html
> Sent from the R help mailing list archive at Nabble.com.
> 
> ______________________________________________
> R-help at r-project.org mailing list
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> PLEASE do read the posting guide
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> and provide commented, minimal, self-contained, reproducible code.
-- 
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of erinu
> Sent: Wednesday, October 23, 2013 11:14 AM
> To: r-help at r-project.org
> Subject: [R] How to view un-sampled data from a randomly sampled
> dataset
> 
> Hi there-
> 
> I have a 150 row dataset (data). I create "y" a randomly sampled
> (without
> replacement) set number of observations (40):
> 
> y<-data[sample(1:nrow(data),40,replace=FALSE),]
> 
> I would like to make a new variable "x" that contains the
leftover
> non-sampled 110 observations.  I am sure there is a fairly easy way to
> do
> this.
> 
> Any help would be greatly appreciated.
> 
> THANKS!
> 
> 
Perhaps something like

ndx <- sample(1:nrow(data),40,replace=FALSE)
y <- data[ndx,]
x <- data[-ndx,]


hope this is helpful,

Dan

Daniel J. Nordlund, PhD
Research and Data Analysis Division
Services & Enterprise Support Administration
Washington State Department of Social and Health Services