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ask for help
8 messages · Johnnycz, jim holtman, Peter Dalgaard +2 more
rle Jim Holtman Data Munger Guru What is the problem that you are trying to solve? Tell me what you want to do, not how you want to do it.
On Wed, Aug 6, 2014 at 10:12 PM, Johnnycz <johnnycz at yeah.net> wrote:
Hello,everybody,
I have a sequence,like a<-c(1,1,1,0,0,1,1,1,1,1,1,0,0,0,0,1,1,0,0,0,0,0,1,1,1,1,1,1,1,1,1,1,1),how to get the position of each first 1 and 0, that's to say, how to get b<-c(1,6,16,23) for first 1 and d<-c(4,12,18) for first 0.
Many thanks!
Johnny
[[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.
a<-c(1,1,1,0,0,1,1,1,1,1,1,0,0,0,0,1,1,0,0,0,0,0,1,1,1,1,1,1,1,1,1,1,1) which( a==1 & c(TRUE, a[-length(a)]!=1) )
[1] 1 6 16 23
which( a==0 & c(TRUE, a[-length(a)]!=0) )
[1] 4 12 18 Bill Dunlap TIBCO Software wdunlap tibco.com
On Wed, Aug 6, 2014 at 7:12 PM, Johnnycz <johnnycz at yeah.net> wrote:
Hello,everybody,
I have a sequence,like a<-c(1,1,1,0,0,1,1,1,1,1,1,0,0,0,0,1,1,0,0,0,0,0,1,1,1,1,1,1,1,1,1,1,1),how to get the position of each first 1 and 0, that's to say, how to get b<-c(1,6,16,23) for first 1 and d<-c(4,12,18) for first 0.
Many thanks!
Johnny
[[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.
On 07 Aug 2014, at 11:16 , jim holtman <jholtman at gmail.com> wrote:
rle
...with a little tinkering, like
m <- c(1,cumsum(rle(a)$lengths)+1) m
[1] 1 4 6 12 16 18 23 34 then look at every 2nd element, discarding the last.
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
My solution may be a bit clearer if you define the function isFirstInRun
isFirstInRun <- function(x) {
if (length(x) == 0) {
logical(0)
} else {
c(TRUE, x[-1] != x[-length(x)])
}
}
Then that solution is equivalent to
which(isFirstInRun(a) & a==1)
If 'a' contains NA's then you have to decide how to deal with them.
(The call to 'which' is not needed if you are going to be using the
result as a subscript.)
You may also want isLastInRun
isLastInRun <- function(x) {
if (length(x) == 0) {
logical(0)
} else {
c(x[-1] != x[-length(x)], TRUE)
}
}
Bill Dunlap
TIBCO Software
wdunlap tibco.com
On Thu, Aug 7, 2014 at 7:36 AM, William Dunlap <wdunlap at tibco.com> wrote:
a<-c(1,1,1,0,0,1,1,1,1,1,1,0,0,0,0,1,1,0,0,0,0,0,1,1,1,1,1,1,1,1,1,1,1) which( a==1 & c(TRUE, a[-length(a)]!=1) )
[1] 1 6 16 23
which( a==0 & c(TRUE, a[-length(a)]!=0) )
[1] 4 12 18 Bill Dunlap TIBCO Software wdunlap tibco.com On Wed, Aug 6, 2014 at 7:12 PM, Johnnycz <johnnycz at yeah.net> wrote:
Hello,everybody,
I have a sequence,like a<-c(1,1,1,0,0,1,1,1,1,1,1,0,0,0,0,1,1,0,0,0,0,0,1,1,1,1,1,1,1,1,1,1,1),how to get the position of each first 1 and 0, that's to say, how to get b<-c(1,6,16,23) for first 1 and d<-c(4,12,18) for first 0.
Many thanks!
Johnny
[[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.
For readability I like:
b <- c(0,a[-length(a)]) which(a != b & a == 0)
[1] 4 12 18
which(a != b & a == 1)
[1] 1 6 16 23
On 07 Aug 2014, at 17:23, William Dunlap <wdunlap at tibco.com> wrote:
My solution may be a bit clearer if you define the function isFirstInRun
isFirstInRun <- function(x) {
if (length(x) == 0) {
logical(0)
} else {
c(TRUE, x[-1] != x[-length(x)])
}
}
Then that solution is equivalent to
which(isFirstInRun(a) & a==1)
If 'a' contains NA's then you have to decide how to deal with them.
(The call to 'which' is not needed if you are going to be using the
result as a subscript.)
You may also want isLastInRun
isLastInRun <- function(x) {
if (length(x) == 0) {
logical(0)
} else {
c(x[-1] != x[-length(x)], TRUE)
}
}
Bill Dunlap
TIBCO Software
wdunlap tibco.com
On Thu, Aug 7, 2014 at 7:36 AM, William Dunlap <wdunlap at tibco.com> wrote:
a<-c(1,1,1,0,0,1,1,1,1,1,1,0,0,0,0,1,1,0,0,0,0,0,1,1,1,1,1,1,1,1,1,1,1) which( a==1 & c(TRUE, a[-length(a)]!=1) )
[1] 1 6 16 23
which( a==0 & c(TRUE, a[-length(a)]!=0) )
[1] 4 12 18 Bill Dunlap TIBCO Software wdunlap tibco.com On Wed, Aug 6, 2014 at 7:12 PM, Johnnycz <johnnycz at yeah.net> wrote:
Hello,everybody,
I have a sequence,like a<-c(1,1,1,0,0,1,1,1,1,1,1,0,0,0,0,1,1,0,0,0,0,0,1,1,1,1,1,1,1,1,1,1,1),how to get the position of each first 1 and 0, that's to say, how to get b<-c(1,6,16,23) for first 1 and d<-c(4,12,18) for first 0.
Many thanks!
Johnny
[[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.
______________________________________________ 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.
Better: b <- c(a[1]-1,a[-length(a)])
On 07 Aug 2014, at 17:28, Bart Kastermans <kasterma at kasterma.net> wrote:
For readability I like:
b <- c(0,a[-length(a)]) which(a != b & a == 0)
[1] 4 12 18
which(a != b & a == 1)
[1] 1 6 16 23 On 07 Aug 2014, at 17:23, William Dunlap <wdunlap at tibco.com> wrote:
My solution may be a bit clearer if you define the function isFirstInRun
isFirstInRun <- function(x) {
if (length(x) == 0) {
logical(0)
} else {
c(TRUE, x[-1] != x[-length(x)])
}
}
Then that solution is equivalent to
which(isFirstInRun(a) & a==1)
If 'a' contains NA's then you have to decide how to deal with them.
(The call to 'which' is not needed if you are going to be using the
result as a subscript.)
You may also want isLastInRun
isLastInRun <- function(x) {
if (length(x) == 0) {
logical(0)
} else {
c(x[-1] != x[-length(x)], TRUE)
}
}
Bill Dunlap
TIBCO Software
wdunlap tibco.com
On Thu, Aug 7, 2014 at 7:36 AM, William Dunlap <wdunlap at tibco.com> wrote:
a<-c(1,1,1,0,0,1,1,1,1,1,1,0,0,0,0,1,1,0,0,0,0,0,1,1,1,1,1,1,1,1,1,1,1) which( a==1 & c(TRUE, a[-length(a)]!=1) )
[1] 1 6 16 23
which( a==0 & c(TRUE, a[-length(a)]!=0) )
[1] 4 12 18 Bill Dunlap TIBCO Software wdunlap tibco.com On Wed, Aug 6, 2014 at 7:12 PM, Johnnycz <johnnycz at yeah.net> wrote:
Hello,everybody,
I have a sequence,like a<-c(1,1,1,0,0,1,1,1,1,1,1,0,0,0,0,1,1,0,0,0,0,0,1,1,1,1,1,1,1,1,1,1,1),how to get the position of each first 1 and 0, that's to say, how to get b<-c(1,6,16,23) for first 1 and d<-c(4,12,18) for first 0.
Many thanks!
Johnny
[[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.
______________________________________________ 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.
I prefer the idiom c(TRUE, a[-1] != a[-length(x)]) because it works for character and other data types as well. I also find that thinking in terms of runs instead of subscripting tricks is easier.