From: Martin Maechler <maechler_at_stat.math.ethz.ch>

Date: Wed 22 Jun 2005 - 18:13:27 EST

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 Received on Wed Jun 22 18:16:59 2005

Date: Wed 22 Jun 2005 - 18:13:27 EST

>>>>> "AndyL" == Liaw, Andy <andy_liaw@merck.com> >>>>> on Tue, 21 Jun 2005 13:30:54 -0400 writes:

AndyL> Try:

>> (x <- factor(1:2, levels=1:5))

AndyL> [1] 1 2

AndyL> Levels: 1 2 3 4 5

>> (x <- x[, drop=TRUE])

AndyL> [1] 1 2

AndyL> Levels: 1 2

or

(x <- factor(1:2, levels=1:5))

(x2 <- factor(x))

which also drops the level

Martin

AndyL> Andy

>> From: Weiwei Shi [mailto:helprhelp@gmail.com]

* >>
** >> Even before I tried, I already realize it must be true when I read
** >> this reply! Great job! thanks, Andy.
** >>
** >> > str(z)
** >> `data.frame': 235 obs. of 2 variables:
** >> $ CLAIMNUM : Factor w/ 1907 levels "0","10000001849",..: 1083 1083
** >> 1083 1582 1582 1084 1681 1681 1391 1391 ...
** >> $ SIU.SAVED: int 475 3000 3000 0 0 4352 0 0 4500 3000 ...
** >>
** >> So, I have another general question: how to avoid this when I
** >> do the matching?
** >> In my case, claimnum does not have to be a factor. I think I can do
** >> as.integer on it to de-factor it. But, I want to know how to do it w/
** >> keeping is as factor? btw, what's your way to drop those levels? :)
** >>
** >> weiwei
** >>
** >>
** >> On 6/21/05, Liaw, Andy <andy_liaw@merck.com> wrote:
** >> > What does str(z) say? I suspect the second column is a
** >> factor, which, after
** >> > the subsetting, has some empty levels. If so, just drop
** >> those levels.
** >> >
** >> > Andy
** >> >
** >> > > From: Weiwei Shi
** >> > >
** >> > > hi
** >> > > i tried all the methods suggested above:
** >> > > ave and rowsum with "with" function works for my
** >> situation. I think
** >> > > the problem might not be due to tapply.
** >> > > My data z comes from
** >> > > z<-y[y[[1]] %in% x[[2]], c(1,9)]
** >> > >
** >> > > while z is supposed to have no entries for those non-matched
** >> > > between x and y.
** >> > >
** >> > > however, when I run tapply, and the result also includes those
** >> > > non-matched entries. I use is.na function to remove those
** >> entry from z
** >> > > first and then use tapply again, but the result is the same: those
** >> > > NA's and those non-matched results are still there.
** >> That's what I mean
** >> > > by "it doesn't work".
** >> > >
** >> > > Is there something I missed here so that z "implicitly" has some
** >> > > "trace" back to y dataset?
** >> > >
** >> > > thanks,
** >> > >
** >> > > On 6/20/05, Gabor Grothendieck <ggrothendieck@gmail.com> wrote:
** >> > > > On 6/20/05, Weiwei Shi <helprhelp@gmail.com> wrote:
** >> > > > > hi,
** >> > > > > i have another question on tapply:
** >> > > > > i have a dataset z like this:
** >> > > > > 5540 389100307391 2600
** >> > > > > 5541 389100307391 2600
** >> > > > > 5542 389100307391 2600
** >> > > > > 5543 389100307391 2600
** >> > > > > 5544 389100307391 2600
** >> > > > > 5546 381300302513 NA
** >> > > > > 5547 387000307470 NA
** >> > > > > 5548 387000307470 NA
** >> > > > > 5549 387000307470 NA
** >> > > > > 5550 387000307470 NA
** >> > > > > 5551 387000307470 NA
** >> > > > > 5552 387000307470 NA
** >> > > > >
** >> > > > > I want to sum the column 3 by column 2.
** >> > > > > I removed NA by calling:
** >> > > > > tapply(z[[3]], z[[2]], sum, na.rm=T)
** >> > > > > but it does not work.
** >> > > > >
** >> > > > > then, i used
** >> > > > > z1<-z[!is.na(z[[3]],]
** >> > > > > and repeat
** >> > > > > still doesn't work.
** >> > > > >
** >> > > > > please help.
** >> > > > >
** >> > > >
** >> > > > Depending on what you want you may be able to use rowsum:
** >> > > >
** >> > > > - display only groups that have at least one non-NA with the sum
** >> > > > being the sum of the non-NAs:
** >> > > >
** >> > > > with(na.omit(z), rowsum(V3, V2))
** >> > > >
** >> > > > - display all groups with the sum being NA if any member is NA:
** >> > > >
** >> > > > rowsum(z$V3, z$V2)
** >> > > >
** >> > >
** >> > >
** >> > > --
** >> > > Weiwei Shi, Ph.D
** >> > >
** >> > > "Did you always know?"
** >> > > "No, I did not. But I believed..."
** >> > > ---Matrix III
** >> > >
** >> > > ______________________________________________
** >> > > 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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** >>
** >>
** >> --
** >> Weiwei Shi, Ph.D
** >>
** >> "Did you always know?"
** >> "No, I did not. But I believed..."
** >> ---Matrix III
** >>
** >>
** >>
*

AndyL> ______________________________________________ AndyL> R-help@stat.math.ethz.ch mailing listAndyL> https://stat.ethz.ch/mailman/listinfo/r-help AndyL> PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html

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 Received on Wed Jun 22 18:16:59 2005

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