Re: [R] the first. from SAS in R
My apologies for coming to the party so late. I'm sure this question has been answered a couple of times. The attached function is one I pulled from the help archives, but I can't seem to duplicate the search that led me to it. In any case, I've attached the function I found, and an .Rd file I use as part of a local package. I've also attached a pair of accompanying records to retrieve the last record and the nth record. These have the advantage of not requiring data frames to be sorted prior to extraction--the function will sort them for you. Benjamin -Original Message- From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On Behalf Of David Katz Sent: Wednesday, November 24, 2010 10:17 AM To: r-help@r-project.org Subject: Re: [R] the first. from SAS in R Often the purpose of first/last in sas is to facilitate grouping of observations in a sequential algorithm. This purpose is better served in R by using vectorized methods like those in package plyr. Also, note that first/last has different meanings in the context of by x; versus by x notsorted;. R duplicated does not address the latter, which splits noncontiguous records with equal x. Regards, David -- View this message in context: http://r.789695.n4.nabble.com/the-first-from-SAS-in-R-tp3055417p3057476. html Sent from the R help mailing list archive at Nabble.com. __ R-help@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. === P Please consider the environment before printing this e-mail Cleveland Clinic is ranked one of the top hospitals in America by U.S.News World Report (2009). Visit us online at http://www.clevelandclinic.org for a complete listing of our services, staff and locations. Confidentiality Note: This message is intended for use only by the individual or entity to which it is addressed and may contain information that is privileged, confidential, and exempt from disclosure under applicable law. If the reader of this message is not the intended recipient or the employee or agent responsible for delivering the message to the intended recipient, you are hereby notified that any dissemination, distribution or copying of this communication is strictly prohibited. If you have received this communication in error, please contact the sender immediately and destroy the material in its entirety, whether electronic or hard copy. Thank you. __ R-help@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.
Re: [R] the first. from SAS in R
Often the purpose of first/last in sas is to facilitate grouping of observations in a sequential algorithm. This purpose is better served in R by using vectorized methods like those in package plyr. Also, note that first/last has different meanings in the context of by x; versus by x notsorted;. R duplicated does not address the latter, which splits noncontiguous records with equal x. Regards, David -- View this message in context: http://r.789695.n4.nabble.com/the-first-from-SAS-in-R-tp3055417p3057476.html Sent from the R help mailing list archive at Nabble.com. __ R-help@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.
Re: [R] the first. from SAS in R
Perhaps something like this:
a$d - ifelse(duplicated(a$a), 0, 1)
On Tue, Nov 23, 2010 at 1:33 PM, Joel joda2...@student.uu.se wrote:
Is there any similar function in R to the first. in SAS?
What it dose is:
Lets say we have this table:
a b c
1 1 5
1 0 2
2 0 2
2 0 NA
2 9 2
3 1 3
and then I want do to do one thing the first time the number 1 appers in a
and something else the secund time 1 appers in a and so on.
so
something similar to:
if first.a {
a$d-1
}else{
a$d-0
}
This would give me
a b c b
1 1 5 1
1 0 2 0
2 0 2 1
2 0 NA 0
2 9 2 0
3 1 3 1
Is there such a function in R or anything similar?
thx
//Joel
--
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Re: [R] the first. from SAS in R
On Nov 23, 2010, at 8:33 AM, Joel wrote:
Is there any similar function in R to the first. in SAS?
What it dose is:
Lets say we have this table:
a b c
1 1 5
1 0 2
2 0 2
2 0 NA
2 9 2
3 1 3
and then I want do to do one thing the first time the number 1
appers in a
and something else the secund time 1 appers in a and so on.
so
something similar to:
if first.a {
a$d-1
}else{
a$d-0
}
The duplicated function which returns a logical vector with those
features can easily be coerced to numeric.
df$d - as.numeric(!duplicated(df$a))
I was a bit puzzled about my failure to get coercion by the method
which I thought was supposed to work, namely adding 0.
df$e - !duplicated(df$a)+0 # does not coerce
df$e - 0 + !duplicated(df$a) # pre-adding 0 does coerce
Maybe the rules on coercion were amended.
--
David
This would give me
a b c b
1 1 5 1
1 0 2 0
2 0 2 1
2 0 NA 0
2 9 2 0
3 1 3 1
Is there such a function in R or anything similar?
thx
//Joel
--
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http://r.789695.n4.nabble.com/the-first-from-SAS-in-R-tp3055417p3055417.html
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__
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David Winsemius, MD
West Hartford, CT
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Re: [R] the first. from SAS in R
Interesting. Check this out:
u - sample(c(TRUE, FALSE), 10, replace = TRUE)
u
[1] FALSE FALSE TRUE FALSE FALSE TRUE FALSE FALSE FALSE FALSE
class(u)
[1] logical
u + 0
[1] 0 0 1 0 0 1 0 0 0 0
0 + u
[1] 0 0 1 0 0 1 0 0 0 0
v - rpois(10, 3)
!duplicated(v)
[1] TRUE FALSE TRUE TRUE TRUE TRUE FALSE TRUE FALSE TRUE
class(!duplicated(v))
[1] logical
!duplicated(v) + 0
[1] TRUE FALSE TRUE TRUE TRUE TRUE FALSE TRUE FALSE TRUE
0 + !duplicated(v)
[1] 1 0 1 1 1 1 0 1 0 1
# Now assign !duplicated(v) to an object:
w - !duplicated(v)
class(w)
[1] logical
0 + w
[1] 1 0 1 1 1 1 0 1 0 1
w + 0
[1] 1 0 1 1 1 1 0 1 0 1
I can see *what* is going on, but what is the reason for it? I see another
notebook entry coming :)
Dennis
On Tue, Nov 23, 2010 at 6:12 AM, David Winsemius dwinsem...@comcast.netwrote:
On Nov 23, 2010, at 8:33 AM, Joel wrote:
Is there any similar function in R to the first. in SAS?
What it dose is:
Lets say we have this table:
a b c
1 1 5
1 0 2
2 0 2
2 0 NA
2 9 2
3 1 3
and then I want do to do one thing the first time the number 1 appers in a
and something else the secund time 1 appers in a and so on.
so
something similar to:
if first.a {
a$d-1
}else{
a$d-0
}
The duplicated function which returns a logical vector with those features
can easily be coerced to numeric.
df$d - as.numeric(!duplicated(df$a))
I was a bit puzzled about my failure to get coercion by the method which I
thought was supposed to work, namely adding 0.
df$e - !duplicated(df$a)+0 # does not coerce
df$e - 0 + !duplicated(df$a) # pre-adding 0 does coerce
Maybe the rules on coercion were amended.
--
David
This would give me
a b c b
1 1 5 1
1 0 2 0
2 0 2 1
2 0 NA 0
2 9 2 0
3 1 3 1
Is there such a function in R or anything similar?
thx
//Joel
--
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http://r.789695.n4.nabble.com/the-first-from-SAS-in-R-tp3055417p3055417.html
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__
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and provide commented, minimal, self-contained, reproducible code.
David Winsemius, MD
West Hartford, CT
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Re: [R] the first. from SAS in R
On Tue, 23 Nov 2010, Joel wrote:
Is there any similar function in R to the first. in SAS?
What it dose is:
Lets say we have this table:
a b c
1 1 5
1 0 2
2 0 2
2 0 NA
2 9 2
3 1 3
and then I want do to do one thing the first time the number 1 appers in a
and something else the secund time 1 appers in a and so on.
so
something similar to:
if first.a {
a$d-1
}else{
a$d-0
}
This would give me
a b c b
1 1 5 1
1 0 2 0
2 0 2 1
2 0 NA 0
2 9 2 0
3 1 3 1
Is there such a function in R or anything similar?
See
?duplicated
then try
a$d - ifelse( duplicated( a$a ), 0 , 1 )
and
a$d.2 - as.numeric( !duplicated( a$a ) )
HTH,
Chuck
thx
//Joel
--
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Charles C. BerryDept of Family/Preventive Medicine
cbe...@tajo.ucsd.eduUC San Diego
http://famprevmed.ucsd.edu/faculty/cberry/ La Jolla, San Diego 92093-0901
__
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Re: [R] the first. from SAS in R
On Tue, 23 Nov 2010, Dennis Murphy wrote:
Interesting. Check this out:
u - sample(c(TRUE, FALSE), 10, replace = TRUE)
u
[1] FALSE FALSE TRUE FALSE FALSE TRUE FALSE FALSE FALSE FALSE
class(u)
[1] logical
u + 0
[1] 0 0 1 0 0 1 0 0 0 0
0 + u
[1] 0 0 1 0 0 1 0 0 0 0
v - rpois(10, 3)
!duplicated(v)
[1] TRUE FALSE TRUE TRUE TRUE TRUE FALSE TRUE FALSE TRUE
class(!duplicated(v))
[1] logical
!duplicated(v) + 0
[1] TRUE FALSE TRUE TRUE TRUE TRUE FALSE TRUE FALSE TRUE
0 + !duplicated(v)
[1] 1 0 1 1 1 1 0 1 0 1
# Now assign !duplicated(v) to an object:
w - !duplicated(v)
class(w)
[1] logical
0 + w
[1] 1 0 1 1 1 1 0 1 0 1
w + 0
[1] 1 0 1 1 1 1 0 1 0 1
I can see *what* is going on, but what is the reason for it? I see another
notebook entry coming :)
See
?Arithmetic
and read the paragraph under Details starting 'Logical vectors'
Chuck
Dennis
On Tue, Nov 23, 2010 at 6:12 AM, David Winsemius dwinsem...@comcast.netwrote:
On Nov 23, 2010, at 8:33 AM, Joel wrote:
Is there any similar function in R to the first. in SAS?
What it dose is:
Lets say we have this table:
a b c
1 1 5
1 0 2
2 0 2
2 0 NA
2 9 2
3 1 3
and then I want do to do one thing the first time the number 1 appers in a
and something else the secund time 1 appers in a and so on.
so
something similar to:
if first.a {
a$d-1
}else{
a$d-0
}
The duplicated function which returns a logical vector with those features
can easily be coerced to numeric.
df$d - as.numeric(!duplicated(df$a))
I was a bit puzzled about my failure to get coercion by the method which I
thought was supposed to work, namely adding 0.
df$e - !duplicated(df$a)+0 # does not coerce
df$e - 0 + !duplicated(df$a) # pre-adding 0 does coerce
Maybe the rules on coercion were amended.
--
David
This would give me
a b c b
1 1 5 1
1 0 2 0
2 0 2 1
2 0 NA 0
2 9 2 0
3 1 3 1
Is there such a function in R or anything similar?
thx
//Joel
--
View this message in context:
http://r.789695.n4.nabble.com/the-first-from-SAS-in-R-tp3055417p3055417.html
Sent from the R help mailing list archive at Nabble.com.
__
R-help@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
West Hartford, CT
__
R-help@r-project.org mailing list
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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@r-project.org mailing list
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Charles C. BerryDept of Family/Preventive Medicine
cbe...@tajo.ucsd.eduUC San Diego
http://famprevmed.ucsd.edu/faculty/cberry/ La Jolla, San Diego 92093-0901
__
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Re: [R] the first. from SAS in R
It all has to do with the precedence of the ! operator.
Compare !duplicated(v) + 0 with (!duplicated(v)) + 0
Dave
From:
Charles C. Berry cbe...@tajo.ucsd.edu
To:
Dennis Murphy djmu...@gmail.com
Cc:
r-help@r-project.org
Date:
11/23/2010 10:08 AM
Subject:
Re: [R] the first. from SAS in R
Sent by:
r-help-boun...@r-project.org
On Tue, 23 Nov 2010, Dennis Murphy wrote:
Interesting. Check this out:
u - sample(c(TRUE, FALSE), 10, replace = TRUE)
u
[1] FALSE FALSE TRUE FALSE FALSE TRUE FALSE FALSE FALSE FALSE
class(u)
[1] logical
u + 0
[1] 0 0 1 0 0 1 0 0 0 0
0 + u
[1] 0 0 1 0 0 1 0 0 0 0
v - rpois(10, 3)
!duplicated(v)
[1] TRUE FALSE TRUE TRUE TRUE TRUE FALSE TRUE FALSE TRUE
class(!duplicated(v))
[1] logical
!duplicated(v) + 0
[1] TRUE FALSE TRUE TRUE TRUE TRUE FALSE TRUE FALSE TRUE
0 + !duplicated(v)
[1] 1 0 1 1 1 1 0 1 0 1
# Now assign !duplicated(v) to an object:
w - !duplicated(v)
class(w)
[1] logical
0 + w
[1] 1 0 1 1 1 1 0 1 0 1
w + 0
[1] 1 0 1 1 1 1 0 1 0 1
I can see *what* is going on, but what is the reason for it? I see
another
notebook entry coming :)
See
?Arithmetic
and read the paragraph under Details starting 'Logical vectors'
Chuck
Dennis
On Tue, Nov 23, 2010 at 6:12 AM, David Winsemius
dwinsem...@comcast.netwrote:
On Nov 23, 2010, at 8:33 AM, Joel wrote:
Is there any similar function in R to the first. in SAS?
What it dose is:
Lets say we have this table:
a b c
1 1 5
1 0 2
2 0 2
2 0 NA
2 9 2
3 1 3
and then I want do to do one thing the first time the number 1 appers
in a
and something else the secund time 1 appers in a and so on.
so
something similar to:
if first.a {
a$d-1
}else{
a$d-0
}
The duplicated function which returns a logical vector with those
features
can easily be coerced to numeric.
df$d - as.numeric(!duplicated(df$a))
I was a bit puzzled about my failure to get coercion by the method
which I
thought was supposed to work, namely adding 0.
df$e - !duplicated(df$a)+0 # does not coerce
df$e - 0 + !duplicated(df$a) # pre-adding 0 does coerce
Maybe the rules on coercion were amended.
--
David
This would give me
a b c b
1 1 5 1
1 0 2 0
2 0 2 1
2 0 NA 0
2 9 2 0
3 1 3 1
Is there such a function in R or anything similar?
thx
//Joel
--
View this message in context:
http://r.789695.n4.nabble.com/the-first-from-SAS-in-R-tp3055417p3055417.html
Sent from the R help mailing list archive at Nabble.com.
__
R-help@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
West Hartford, CT
__
R-help@r-project.org mailing list
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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@r-project.org mailing list
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PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Charles C. BerryDept of Family/Preventive
Medicine
cbe...@tajo.ucsd.edu UC
San Diego
http://famprevmed.ucsd.edu/faculty/cberry/ La Jolla, San Diego 92093-0901
__
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PLEASE do read the posting guide
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and provide commented, minimal, self-contained, reproducible code.
[[alternative HTML version deleted]]
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and provide commented, minimal, self-contained, reproducible code.
Re: [R] the first. from SAS in R
On Nov 23, 2010, at 11:04 AM, Charles C. Berry wrote:
On Tue, 23 Nov 2010, Dennis Murphy wrote:
Interesting. Check this out:
u - sample(c(TRUE, FALSE), 10, replace = TRUE)
u
[1] FALSE FALSE TRUE FALSE FALSE TRUE FALSE FALSE FALSE FALSE
class(u)
[1] logical
u + 0
[1] 0 0 1 0 0 1 0 0 0 0
0 + u
[1] 0 0 1 0 0 1 0 0 0 0
v - rpois(10, 3)
!duplicated(v)
[1] TRUE FALSE TRUE TRUE TRUE TRUE FALSE TRUE FALSE TRUE
class(!duplicated(v))
[1] logical
!duplicated(v) + 0
[1] TRUE FALSE TRUE TRUE TRUE TRUE FALSE TRUE FALSE TRUE
0 + !duplicated(v)
[1] 1 0 1 1 1 1 0 1 0 1
# Now assign !duplicated(v) to an object:
w - !duplicated(v)
class(w)
[1] logical
0 + w
[1] 1 0 1 1 1 1 0 1 0 1
w + 0
[1] 1 0 1 1 1 1 0 1 0 1
I can see *what* is going on, but what is the reason for it? I see
another
notebook entry coming :)
See
?Arithmetic
and read the paragraph under Details starting 'Logical vectors'
Chuck;
Compare these three, all of which are using binary operators on
logical vectors which is what is being discussed in ?Arithmetic:
duplicated(c(a, a, b) ) + 0
[1] 0 1 0
!duplicated(c(a, a, b) ) + 0
[1] TRUE FALSE TRUE
0 + !duplicated(c(a, a, b) )
[1] 1 0 1
I believe the proper place to go is ?Syntax where operator precedence
is discussed. I think the precendence rules implicitly do this in the
second instance, because + has higher precendence than negation:
! ( duplicated(c(a, a, b) ) + 0 )
--
David.
Chuck
Dennis
On Tue, Nov 23, 2010 at 6:12 AM, David Winsemius dwinsem...@comcast.net
wrote:
On Nov 23, 2010, at 8:33 AM, Joel wrote:
Is there any similar function in R to the first. in SAS?
What it dose is:
Lets say we have this table:
a b c
1 1 5
1 0 2
2 0 2
2 0 NA
2 9 2
3 1 3
and then I want do to do one thing the first time the number 1
appers in a
and something else the secund time 1 appers in a and so on.
so
something similar to:
if first.a {
a$d-1
}else{
a$d-0
}
The duplicated function which returns a logical vector with those
features
can easily be coerced to numeric.
df$d - as.numeric(!duplicated(df$a))
I was a bit puzzled about my failure to get coercion by the method
which I
thought was supposed to work, namely adding 0.
df$e - !duplicated(df$a)+0 # does not coerce
df$e - 0 + !duplicated(df$a) # pre-adding 0 does coerce
Maybe the rules on coercion were amended.
--
David
This would give me
a b c b
1 1 5 1
1 0 2 0
2 0 2 1
2 0 NA 0
2 9 2 0
3 1 3 1
Is there such a function in R or anything similar?
thx
//Joel
--
View this message in context:
http://r.789695.n4.nabble.com/the-first-from-SAS-in-R-tp3055417p3055417.html
Sent from the R help mailing list archive at Nabble.com.
__
R-help@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
West Hartford, CT
__
R-help@r-project.org mailing list
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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@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.
Charles C. BerryDept of Family/
Preventive Medicine
cbe...@tajo.ucsd.eduUC San Diego
http://famprevmed.ucsd.edu/faculty/cberry/ La Jolla, San Diego
92093-0901
David Winsemius, MD
West Hartford, CT
__
R-help@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.
Re: [R] the first. from SAS in R
On Tue, 23 Nov 2010, David Winsemius wrote:
On Nov 23, 2010, at 11:04 AM, Charles C. Berry wrote:
On Tue, 23 Nov 2010, Dennis Murphy wrote:
Interesting. Check this out:
u - sample(c(TRUE, FALSE), 10, replace = TRUE)
u
[1] FALSE FALSE TRUE FALSE FALSE TRUE FALSE FALSE FALSE FALSE
class(u)
[1] logical
u + 0
[1] 0 0 1 0 0 1 0 0 0 0
0 + u
[1] 0 0 1 0 0 1 0 0 0 0
v - rpois(10, 3)
!duplicated(v)
[1] TRUE FALSE TRUE TRUE TRUE TRUE FALSE TRUE FALSE TRUE
class(!duplicated(v))
[1] logical
!duplicated(v) + 0
[1] TRUE FALSE TRUE TRUE TRUE TRUE FALSE TRUE FALSE TRUE
0 + !duplicated(v)
[1] 1 0 1 1 1 1 0 1 0 1
# Now assign !duplicated(v) to an object:
w - !duplicated(v)
class(w)
[1] logical
0 + w
[1] 1 0 1 1 1 1 0 1 0 1
w + 0
[1] 1 0 1 1 1 1 0 1 0 1
I can see *what* is going on, but what is the reason for it? I see
another
notebook entry coming :)
See
?Arithmetic
and read the paragraph under Details starting 'Logical vectors'
Chuck;
Compare these three, all of which are using binary operators on logical
vectors which is what is being discussed in ?Arithmetic:
duplicated(c(a, a, b) ) + 0
[1] 0 1 0
!duplicated(c(a, a, b) ) + 0
[1] TRUE FALSE TRUE
0 + !duplicated(c(a, a, b) )
[1] 1 0 1
I believe the proper place to go is ?Syntax where operator precedence is
discussed. I think the precendence rules implicitly do this in the second
instance, because + has higher precendence than negation:
! ( duplicated(c(a, a, b) ) + 0 )
David,
Thanks.
Both you and David Lorenz are correct in pointing to operator precedence
as the answer to Dennis' question.
Mea culpa for my not reading Dennis' question carefully enough to
understand what his question really was!
Best,
Chuck
--
David.
Chuck
Dennis
On Tue, Nov 23, 2010 at 6:12 AM, David Winsemius
dwinsem...@comcast.netwrote:
On Nov 23, 2010, at 8:33 AM, Joel wrote:
Is there any similar function in R to the first. in SAS?
What it dose is:
Lets say we have this table:
a b c
1 1 5
1 0 2
2 0 2
2 0 NA
2 9 2
3 1 3
and then I want do to do one thing the first time the number 1 appers
in a
and something else the secund time 1 appers in a and so on.
so
something similar to:
if first.a {
a$d-1
}else{
a$d-0
}
The duplicated function which returns a logical vector with those
features
can easily be coerced to numeric.
df$d - as.numeric(!duplicated(df$a))
I was a bit puzzled about my failure to get coercion by the method
which I
thought was supposed to work, namely adding 0.
df$e - !duplicated(df$a)+0 # does not coerce
df$e - 0 + !duplicated(df$a) # pre-adding 0 does coerce
Maybe the rules on coercion were amended.
--
David
This would give me
a b c b
1 1 5 1
1 0 2 0
2 0 2 1
2 0 NA 0
2 9 2 0
3 1 3 1
Is there such a function in R or anything similar?
thx
//Joel
--
View this message in context:
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PLEASE do read the posting guide
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Charles C. BerryDept of Family/Preventive
Medicine
cbe...@tajo.ucsd.eduUC San Diego
http://famprevmed.ucsd.edu/faculty/cberry/ La Jolla, San Diego 92093-0901
David Winsemius, MD
West Hartford, CT
Charles C. BerryDept of Family/Preventive Medicine
cbe...@tajo.ucsd.eduUC San Diego
http://famprevmed.ucsd.edu/faculty/cberry/ La Jolla, San Diego 92093-0901
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
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Re: [R] the first. from SAS in R
Is there any similar function in R to the first. in SAS? ?duplicated a$d - ifelse( duplicated( a$a ), 0 , 1 ) a$d.2 - as.numeric( !duplicated( a$a ) ) Actually, duplicated does not duplicate SAS' first. operator, though it may suffice for the OP's needs. To illustrate, let's start with a dataframe of 3 key columns and some data in x: tt - data.frame(k1 = rep(1:3, each=10), k2 = rep(1:5, each=2, times=3), k3=rep(1:2, times=15), x = 1:30) # Try to mimic what the following SAS datastep would do, # assuming 'tt' is already sorted: # data foo; # set tt; # by k1, k2; # put first.k1=, first.k2=; # run; # SAS' first. operations would result in these values: tt$sas.first.k1 - rep(c(1, rep(0,9)), 3) tt$sas.first.k2 - rep(1:0, 15) # R duplicated() returns these values. You can see they # are the same for k1, but dissimilar after row 10 for k2. tt$duplicated.k1 - 0+!duplicated(tt$k1) tt$duplicated.k2 - 0+!duplicated(tt$k2) # I've found I need to lag a column to mimic SAS' first. # operator, thusly, though perhaps someone else knows # differently. Note this does not work on unordered # dataframes! lag.k1 - c(NA, tt$k1[1:(nrow(tt) - 1)]) tt$r.first.k1 - ifelse(is.na(lag.k1), 1, tt$k1 != lag.k1) lag.k2 - c(NA, tt$k2[1:(nrow(tt) - 1)]) tt$r.first.k2 - ifelse(is.na(lag.k2), 1, tt$k2 != lag.k2) Mimicking SAS' last. operation can be done in a similar manner, by anti-laging the column of interest and changing the comparisons somewhat. Enjoy the days, cur -- Curt Seeliger, Data Ranger Raytheon Information Services - Contractor to ORD seeliger.c...@epa.gov 541/754-4638 [[alternative HTML version deleted]] __ R-help@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.
Re: [R] the first. from SAS in R
On Tue, 23 Nov 2010, seeliger.c...@epamail.epa.gov wrote: Is there any similar function in R to the first. in SAS? ?duplicated a$d - ifelse( duplicated( a$a ), 0 , 1 ) a$d.2 - as.numeric( !duplicated( a$a ) ) Actually, duplicated does not duplicate SAS' first. operator, though it may suffice for the OP's needs. To illustrate, let's start with a dataframe of 3 key columns and some data in x: tt - data.frame(k1 = rep(1:3, each=10), k2 = rep(1:5, each=2, times=3), k3=rep(1:2, times=15), x = 1:30) # Try to mimic what the following SAS datastep would do, # assuming 'tt' is already sorted: # data foo; # set tt; # by k1, k2; # put first.k1=, first.k2=; # run; # SAS' first. operations would result in these values: tt$sas.first.k1 - rep(c(1, rep(0,9)), 3) tt$sas.first.k2 - rep(1:0, 15) # R duplicated() returns these values. You can see they # are the same for k1, but dissimilar after row 10 for k2. tt$duplicated.k1 - 0+!duplicated(tt$k1) tt$duplicated.k2 - 0+!duplicated(tt$k2) It depends on how you use duplicated() all.equal( tt$sas.first.k2, 0+!duplicated( tt[, c(k1,k2) ] ) ) [1] TRUE Chuck # I've found I need to lag a column to mimic SAS' first. # operator, thusly, though perhaps someone else knows # differently. Note this does not work on unordered # dataframes! lag.k1 - c(NA, tt$k1[1:(nrow(tt) - 1)]) tt$r.first.k1 - ifelse(is.na(lag.k1), 1, tt$k1 != lag.k1) lag.k2 - c(NA, tt$k2[1:(nrow(tt) - 1)]) tt$r.first.k2 - ifelse(is.na(lag.k2), 1, tt$k2 != lag.k2) Mimicking SAS' last. operation can be done in a similar manner, by anti-laging the column of interest and changing the comparisons somewhat. Enjoy the days, cur -- Curt Seeliger, Data Ranger Raytheon Information Services - Contractor to ORD seeliger.c...@epa.gov 541/754-4638 [[alternative HTML version deleted]] __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Charles C. BerryDept of Family/Preventive Medicine cbe...@tajo.ucsd.eduUC San Diego http://famprevmed.ucsd.edu/faculty/cberry/ La Jolla, San Diego 92093-0901 __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] the first. from SAS in R
... # I've found I need to lag a column to mimic SAS' first. # operator, thusly, though perhaps someone else knows # differently. Note this does not work on unordered # dataframes! lag.k1 - c(NA, tt$k1[1:(nrow(tt) - 1)]) tt$r.first.k1 - ifelse(is.na(lag.k1), 1, tt$k1 != lag.k1) lag.k2 - c(NA, tt$k2[1:(nrow(tt) - 1)]) tt$r.first.k2 - ifelse(is.na(lag.k2), 1, tt$k2 != lag.k2) It depends on how you use duplicated() all.equal( tt$sas.first.k2, 0+!duplicated( tt[, c(k1,k2) ] ) ) [1] TRUE Wonderful. Concise. Good job. cur -- Curt Seeliger, Data Ranger Raytheon Information Services - Contractor to ORD seeliger.c...@epa.gov 541/754-4638 [[alternative HTML version deleted]] __ R-help@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.
Re: [R] the first. from SAS in R
I often use code like Curt's encapsulated in the
following isFirstInRun function:
isFirstInRun - function(x,...) {
lengthX - length(x)
if (lengthX == 0) return(logical(0))
retVal - c(TRUE, x[-1]!=x[-lengthX])
for(arg in list(...)) {
stopifnot(lengthX == length(arg))
retVal - retVal | c(TRUE, arg[-1]!=arg[-lengthX])
}
if (any(missing-is.na(retVal))) # match rle: NA!=NA
retVal[missing] - TRUE
retVal
}
E.g.,
d - data.frame(log=trunc(log(1:10)), sqrt=trunc(sqrt(1:10)))
within(d, first - isFirstInRun(log))
log sqrt first
101 TRUE
201 FALSE
311 TRUE
412 FALSE
512 FALSE
612 FALSE
712 FALSE
822 TRUE
923 FALSE
10 23 FALSE
# Or look for change in any number of vectors:
within(d, first - isFirstInRun(log, sqrt)) # TRUE if either changes
log sqrt first
101 TRUE
201 FALSE
311 TRUE
412 TRUE
512 FALSE
612 FALSE
712 FALSE
822 TRUE
923 TRUE
10 23 FALSE
To do isLastInRun put the TRUE after the x[-1]!=x[-length(x)]
isLastInRun - function(x,...) {
lengthX - length(x)
if (lengthX == 0) return(logical(0))
retVal - c(x[-1]!=x[-lengthX], TRUE)
for(arg in list(...)) {
stopifnot(lengthX == length(arg))
retVal - retVal | c(arg[-1]!=arg[-lengthX], TRUE)
}
if (any(missing-is.na(retVal))) # match rle: NA!=NA
retVal[missing] - TRUE
retVal
}
Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
-Original Message-
From: r-help-boun...@r-project.org
[mailto:r-help-boun...@r-project.org] On Behalf Of
seeliger.c...@epamail.epa.gov
Sent: Tuesday, November 23, 2010 10:38 AM
To: r-help@r-project.org
Cc: Joel
Subject: Re: [R] the first. from SAS in R
Is there any similar function in R to the first. in SAS?
?duplicated
a$d - ifelse( duplicated( a$a ), 0 , 1 )
a$d.2 - as.numeric( !duplicated( a$a ) )
Actually, duplicated does not duplicate SAS' first. operator,
though it
may suffice for the OP's needs.
To illustrate, let's start with a dataframe of 3 key columns
and some data
in x:
tt - data.frame(k1 = rep(1:3, each=10), k2 = rep(1:5,
each=2, times=3),
k3=rep(1:2, times=15), x = 1:30)
# Try to mimic what the following SAS datastep would do,
# assuming 'tt' is already sorted:
# data foo;
# set tt;
# by k1, k2;
# put first.k1=, first.k2=;
# run;
# SAS' first. operations would result in these values:
tt$sas.first.k1 - rep(c(1, rep(0,9)), 3)
tt$sas.first.k2 - rep(1:0, 15)
# R duplicated() returns these values. You can see they
# are the same for k1, but dissimilar after row 10 for k2.
tt$duplicated.k1 - 0+!duplicated(tt$k1)
tt$duplicated.k2 - 0+!duplicated(tt$k2)
# I've found I need to lag a column to mimic SAS' first.
# operator, thusly, though perhaps someone else knows
# differently. Note this does not work on unordered
# dataframes!
lag.k1 - c(NA, tt$k1[1:(nrow(tt) - 1)])
tt$r.first.k1 - ifelse(is.na(lag.k1), 1, tt$k1 != lag.k1)
lag.k2 - c(NA, tt$k2[1:(nrow(tt) - 1)])
tt$r.first.k2 - ifelse(is.na(lag.k2), 1, tt$k2 != lag.k2)
Mimicking SAS' last. operation can be done in a similar manner, by
anti-laging the column of interest and changing the
comparisons somewhat.
Enjoy the days,
cur
--
Curt Seeliger, Data Ranger
Raytheon Information Services - Contractor to ORD
seeliger.c...@epa.gov
541/754-4638
[[alternative HTML version deleted]]
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http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
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