Re: [R] converting stata's by syntax to R
Chris Wallace [EMAIL PROTECTED] writes: I am struggling with migrating some stata code to R Thanks to all who replied. It was very helpful to see a combination of more direct stata-R translations and more R-ish code. which.max() solves my problem this time, but learning about split(), unsplit() and duplicated() should make such problems fewer in the long run. C. __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
[R] converting stata's by syntax to R
I am struggling with migrating some stata code to R. I have a data
frame containing, sometimes, repeat observations (rows) of the same
family. I want to keep only one observation per family, selecting
that observation according to some other variable. An example data
frame is:
# construct example data
fam - c(1,2,3,3,4,4,4)
wt - c(1,1,0.6,0.4,0.4,0.4,0.2)
keep - c(1,1,1,0,1,0,0)
dat - as.data.frame(cbind(fam,wt,keep))
dat
I want to keep the observation for which wt is a maximum, and where
this doesn't identify a unique observation, to keep just one anyway,
not caring which. Those observations are indicated above by keep==1.
(Note, keep - c(1,1,1,0,0,1,0) would be fine too, but not
c(1,1,1,0,0,0,1)).
The stata code I would use is
bys fam (wt): keep if _n==_N
This is my (long-winded) attempt in R:
# first keep those rows where wt=max_fam(wt)
maxwt - by(dat,dat$fam,function(x) max(x[,2]))
maxwt - sapply(maxwt,[[,1)
maxwt.dat - data.frame(maxwt=maxwt,fam=as.integer(names(maxwt)))
dat - merge(dat,maxwt.dat)
dat - dat[dat$wt==dat$maxwt,]
dat
Now I am stuck - I want to keep either row with fam==4, and have tried
playing around with combinations of sample and apply or by, but with
no success. I can only find an inefficient for-loop solution:
# identify those rows with 1 observation
more - by(dat,dat$fam,function(x) dim(x)[1])
more - sapply(more,[[,1)
more.dat - data.frame(more=more,fam=as.integer(names(more)))
dat - merge(dat,more.dat)
# sample from those for whom more1
result-dat[dat$more==1,]
for(f in unique(dat$fam[dat$more1])) {
rows - rownames(dat[dat$fam==f,])
result - rbind(result,dat[sample(rows,1),])
}
result
I am sure that for something so simple in stata to be so complicated
in R must indicate ignorance of R on my part, but searches of help
files and RSiteSearch hasn't led to any better solution.
Any suggestions would be most helpful! Thanks, C.
__
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Re: [R] converting stata's by syntax to R
try
attach(dat)
dat-dat[order(fam,wt),]
#sort the data ,as the stata's byable command does
lis-by(dat,fam,function(x) x[length(x$fam),])
#equall your stata command ,but return a list.
do.call(rbind,lis)
#to make the list to be a matrix-like result.
fam wt keep
1 1 1.01
2 2 1.01
3 3 0.40
4 4 0.40
=== 2005-08-01 22:24:27 您在来信中写道：===
I am struggling with migrating some stata code to R. I have a data
frame containing, sometimes, repeat observations (rows) of the same
family. I want to keep only one observation per family, selecting
that observation according to some other variable. An example data
frame is:
# construct example data
fam - c(1,2,3,3,4,4,4)
wt - c(1,1,0.6,0.4,0.4,0.4,0.2)
keep - c(1,1,1,0,1,0,0)
dat - as.data.frame(cbind(fam,wt,keep))
dat
I want to keep the observation for which wt is a maximum, and where
this doesn't identify a unique observation, to keep just one anyway,
not caring which. Those observations are indicated above by keep==1.
(Note, keep - c(1,1,1,0,0,1,0) would be fine too, but not
c(1,1,1,0,0,0,1)).
The stata code I would use is
bys fam (wt): keep if _n==_N
This is my (long-winded) attempt in R:
# first keep those rows where wt=max_fam(wt)
maxwt - by(dat,dat$fam,function(x) max(x[,2]))
maxwt - sapply(maxwt,[[,1)
maxwt.dat - data.frame(maxwt=maxwt,fam=as.integer(names(maxwt)))
dat - merge(dat,maxwt.dat)
dat - dat[dat$wt==dat$maxwt,]
dat
Now I am stuck - I want to keep either row with fam==4, and have tried
playing around with combinations of sample and apply or by, but with
no success. I can only find an inefficient for-loop solution:
# identify those rows with 1 observation
more - by(dat,dat$fam,function(x) dim(x)[1])
more - sapply(more,[[,1)
more.dat - data.frame(more=more,fam=as.integer(names(more)))
dat - merge(dat,more.dat)
# sample from those for whom more1
result-dat[dat$more==1,]
for(f in unique(dat$fam[dat$more1])) {
rows - rownames(dat[dat$fam==f,])
result - rbind(result,dat[sample(rows,1),])
}
result
I am sure that for something so simple in stata to be so complicated
in R must indicate ignorance of R on my part, but searches of help
files and RSiteSearch hasn't led to any better solution.
Any suggestions would be most helpful! Thanks, C.
__
R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
= = = = = = = = = = = = = = = = = = = =
2005-08-01
--
Deparment of Sociology
Fudan University
Blog:http://sociology.yculblog.com
__
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Re: [R] converting stata's by syntax to R
Chris Wallace [EMAIL PROTECTED] writes:
I am struggling with migrating some stata code to R. I have a data
frame containing, sometimes, repeat observations (rows) of the same
family. I want to keep only one observation per family, selecting
that observation according to some other variable. An example data
frame is:
# construct example data
fam - c(1,2,3,3,4,4,4)
wt - c(1,1,0.6,0.4,0.4,0.4,0.2)
keep - c(1,1,1,0,1,0,0)
dat - as.data.frame(cbind(fam,wt,keep))
dat
I want to keep the observation for which wt is a maximum, and where
this doesn't identify a unique observation, to keep just one anyway,
not caring which. Those observations are indicated above by keep==1.
(Note, keep - c(1,1,1,0,0,1,0) would be fine too, but not
c(1,1,1,0,0,0,1)).
The stata code I would use is
bys fam (wt): keep if _n==_N
This is my (long-winded) attempt in R:
# first keep those rows where wt=max_fam(wt)
maxwt - by(dat,dat$fam,function(x) max(x[,2]))
maxwt - sapply(maxwt,[[,1)
maxwt.dat - data.frame(maxwt=maxwt,fam=as.integer(names(maxwt)))
dat - merge(dat,maxwt.dat)
dat - dat[dat$wt==dat$maxwt,]
dat
Now I am stuck - I want to keep either row with fam==4, and have tried
playing around with combinations of sample and apply or by, but with
no success. I can only find an inefficient for-loop solution:
# identify those rows with 1 observation
more - by(dat,dat$fam,function(x) dim(x)[1])
more - sapply(more,[[,1)
more.dat - data.frame(more=more,fam=as.integer(names(more)))
dat - merge(dat,more.dat)
# sample from those for whom more1
result-dat[dat$more==1,]
for(f in unique(dat$fam[dat$more1])) {
rows - rownames(dat[dat$fam==f,])
result - rbind(result,dat[sample(rows,1),])
}
result
I am sure that for something so simple in stata to be so complicated
in R must indicate ignorance of R on my part, but searches of help
files and RSiteSearch hasn't led to any better solution.
Any suggestions would be most helpful! Thanks, C.
How about
unsplit(lapply(split(dat,dat$fam),
function(x) seq(length=nrow(x)) == which.max(x$wt)),
dat$fam)
or
do.call(rbind, lapply(split(dat,dat$fam),
function(x) x[which.max(x$wt),]))
or (same thing, basically)
do.call(rbind, by(dat,dat$fam,function(x) x[which.max(x$wt),]))
--
O__ Peter Dalgaard Øster Farimagsgade 5, Entr.B
c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907
__
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Re: [R] converting stata's by syntax to R
Here is one way this can be done
do.call(rbind, by(dat, list(dat$fam) ,function(x) {
+ if(NROW(x)1) return(x[which.max(x$wt),])
+ else return(x)}
+ ))
and it returns
fam wt keep
1 1 1.01
2 2 1.01
3 3 0.61
4 4 0.41
hth,
On Mon, 1 Aug 2005, Chris Wallace wrote:
I am struggling with migrating some stata code to R. I have a data
frame containing, sometimes, repeat observations (rows) of the same
family. I want to keep only one observation per family, selecting
that observation according to some other variable. An example data
frame is:
# construct example data
fam - c(1,2,3,3,4,4,4)
wt - c(1,1,0.6,0.4,0.4,0.4,0.2)
keep - c(1,1,1,0,1,0,0)
dat - as.data.frame(cbind(fam,wt,keep))
dat
I want to keep the observation for which wt is a maximum, and where
this doesn't identify a unique observation, to keep just one anyway,
not caring which. Those observations are indicated above by keep==1.
(Note, keep - c(1,1,1,0,0,1,0) would be fine too, but not
c(1,1,1,0,0,0,1)).
The stata code I would use is
bys fam (wt): keep if _n==_N
This is my (long-winded) attempt in R:
# first keep those rows where wt=max_fam(wt)
maxwt - by(dat,dat$fam,function(x) max(x[,2]))
maxwt - sapply(maxwt,[[,1)
maxwt.dat - data.frame(maxwt=maxwt,fam=as.integer(names(maxwt)))
dat - merge(dat,maxwt.dat)
dat - dat[dat$wt==dat$maxwt,]
dat
Now I am stuck - I want to keep either row with fam==4, and have tried
playing around with combinations of sample and apply or by, but with
no success. I can only find an inefficient for-loop solution:
# identify those rows with 1 observation
more - by(dat,dat$fam,function(x) dim(x)[1])
more - sapply(more,[[,1)
more.dat - data.frame(more=more,fam=as.integer(names(more)))
dat - merge(dat,more.dat)
# sample from those for whom more1
result-dat[dat$more==1,]
for(f in unique(dat$fam[dat$more1])) {
rows - rownames(dat[dat$fam==f,])
result - rbind(result,dat[sample(rows,1),])
}
result
I am sure that for something so simple in stata to be so complicated
in R must indicate ignorance of R on my part, but searches of help
files and RSiteSearch hasn't led to any better solution.
Any suggestions would be most helpful! Thanks, C.
__
R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
__
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Re: [R] converting stata's by syntax to R
if you also need to create the `keep' vector, then you could try this
approach:
fam - c(1,2,3,3,4,4,4)
wt - c(1,1,0.6,0.4,0.4,0.4,0.2)
dat - data.frame(fam, wt)
###
keep - unlist( lapply(split(wt, fam), function(x){
ind - rep(FALSE, length(x))
ind[which.max(x)] - TRUE
ind
}) )
as.numeric(keep)
dat[keep, ]
I hope it helps.
Best,
Dimitris
Dimitris Rizopoulos
Ph.D. Student
Biostatistical Centre
School of Public Health
Catholic University of Leuven
Address: Kapucijnenvoer 35, Leuven, Belgium
Tel: +32/16/336899
Fax: +32/16/337015
Web: http://www.med.kuleuven.be/biostat/
http://www.student.kuleuven.be/~m0390867/dimitris.htm
- Original Message -
From: Chris Wallace [EMAIL PROTECTED]
To: r-help@stat.math.ethz.ch
Sent: Monday, August 01, 2005 4:24 PM
Subject: [R] converting stata's by syntax to R
I am struggling with migrating some stata code to R. I have a data
frame containing, sometimes, repeat observations (rows) of the same
family. I want to keep only one observation per family, selecting
that observation according to some other variable. An example data
frame is:
# construct example data
fam - c(1,2,3,3,4,4,4)
wt - c(1,1,0.6,0.4,0.4,0.4,0.2)
keep - c(1,1,1,0,1,0,0)
dat - as.data.frame(cbind(fam,wt,keep))
dat
I want to keep the observation for which wt is a maximum, and where
this doesn't identify a unique observation, to keep just one anyway,
not caring which. Those observations are indicated above by
keep==1.
(Note, keep - c(1,1,1,0,0,1,0) would be fine too, but not
c(1,1,1,0,0,0,1)).
The stata code I would use is
bys fam (wt): keep if _n==_N
This is my (long-winded) attempt in R:
# first keep those rows where wt=max_fam(wt)
maxwt - by(dat,dat$fam,function(x) max(x[,2]))
maxwt - sapply(maxwt,[[,1)
maxwt.dat -
data.frame(maxwt=maxwt,fam=as.integer(names(maxwt)))
dat - merge(dat,maxwt.dat)
dat - dat[dat$wt==dat$maxwt,]
dat
Now I am stuck - I want to keep either row with fam==4, and have
tried
playing around with combinations of sample and apply or by, but with
no success. I can only find an inefficient for-loop solution:
# identify those rows with 1 observation
more - by(dat,dat$fam,function(x) dim(x)[1])
more - sapply(more,[[,1)
more.dat - data.frame(more=more,fam=as.integer(names(more)))
dat - merge(dat,more.dat)
# sample from those for whom more1
result-dat[dat$more==1,]
for(f in unique(dat$fam[dat$more1])) {
rows - rownames(dat[dat$fam==f,])
result - rbind(result,dat[sample(rows,1),])
}
result
I am sure that for something so simple in stata to be so complicated
in R must indicate ignorance of R on my part, but searches of help
files and RSiteSearch hasn't led to any better solution.
Any suggestions would be most helpful! Thanks, C.
__
R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html
__
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Re: [R] converting stata's by syntax to R
On Mon, 1 Aug 2005, Chris Wallace wrote: I am struggling with migrating some stata code to R. I have a data frame containing, sometimes, repeat observations (rows) of the same family. I want to keep only one observation per family, selecting that observation according to some other variable. An example data frame is: # construct example data fam - c(1,2,3,3,4,4,4) wt - c(1,1,0.6,0.4,0.4,0.4,0.2) keep - c(1,1,1,0,1,0,0) dat - as.data.frame(cbind(fam,wt,keep)) dat I want to keep the observation for which wt is a maximum, and where this doesn't identify a unique observation, to keep just one anyway, not caring which. Those observations are indicated above by keep==1. (Note, keep - c(1,1,1,0,0,1,0) would be fine too, but not c(1,1,1,0,0,0,1)). The stata code I would use is bys fam (wt): keep if _n==_N A reasonably direct translation of the Stata code is index - order(fam, -wt) keep - !duplicated(fam[index]) dat - data.frame(fam=fam[index], wt=wt[index], keep=keep) which sorts wt into decreasing order within family, then keeps the first observation in each family. This is less general than solutions other people have given, but I'd expect it to be faster for large data sets. 'keep' ends up TRUE/FALSE rather than 1/0; if this is a problem use as.numeric() on it. -thomas __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
