Yao He
2012-Dec-27 00:54 UTC
[R] how to apply two or more functions to each columns in a time?
Dear All:
I want to calculate the mean and sd for each column in a data.frame.
Taking data(iris) for example:
I tried sapply(iris[,-5],mean,na.rm=T) or sapply(iris[,-5],sd,na.rm=T)
to calculate the mean and sd .But sapply() transfer a function per
time. How to transfer two functions in a time to generate a data.frame
like this:
Sepal.Length Sepal.Width Petal.Length Petal.Width
mean 5.84333 3.05733 3.758000 1.199333
SD 0.82806 0.43586 1.765298 0.762237
Thanks a lot
Yao He
--
?????????????????????????
Master candidate in 2rd year
Department of Animal genetics & breeding
Room 436,College of Animial Science&Technology,
China Agriculture University,Beijing,100193
E-mail: yao.h.1988 at gmail.com
??????????????????????????
arun
2012-Dec-27 01:11 UTC
[R] how to apply two or more functions to each columns in a time?
Hi, Try this: ?sapply(iris[,-5],function(x) rbind(mean(x,na.rm=T),sd(x,na.rm=T))) #???? Sepal.Length Sepal.Width Petal.Length Petal.Width #[1,]??? 5.8433333?? 3.0573333???? 3.758000?? 1.1993333 #[2,]??? 0.8280661?? 0.4358663???? 1.765298?? 0.7622377 A.K. ----- Original Message ----- From: Yao He <yao.h.1988 at gmail.com> To: r-help at r-project.org Cc: Sent: Wednesday, December 26, 2012 7:54 PM Subject: [R] how to apply two or more functions to each columns in a time? Dear All: I want to calculate the mean and sd for each column in a data.frame. Taking data(iris) for example: I tried sapply(iris[,-5],mean,na.rm=T) or sapply(iris[,-5],sd,na.rm=T) to calculate the mean and sd .But sapply() transfer a function per time. How to transfer two functions in a time to generate a data.frame like this: ? ? ? ? ? Sepal.Length Sepal.Width Petal.Length Petal.Width mean? ? 5.84333? ? ? ? 3.05733? ? ? ? 3.758000? ? ? 1.199333 SD? ? ? ? 0.82806? ? ? ? 0.43586? ? ? ? 1.765298? ? ? 0.762237 Thanks a lot Yao He -- ????????????????????????? Master candidate in 2rd year Department of Animal genetics & breeding Room 436,College of Animial Science&Technology, China Agriculture University,Beijing,100193 E-mail: yao.h.1988 at gmail.com ?????????????????????????? ______________________________________________ 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.
David L Carlson
2012-Dec-27 01:29 UTC
[R] how to apply two or more functions to each columns in a time?
Combine the functions with rbind(). If there are more than two, it will probably be easier to define the function outside sapply.> dta <- sapply(iris[,-5],function(x) rbind(mean(x,na.rm=T), sd(x,na.rm=T))) > rownames(dta) <- c("mean", "SD") > dtaSepal.Length Sepal.Width Petal.Length Petal.Width mean 5.8433333 3.0573333 3.758000 1.1993333 SD 0.8280661 0.4358663 1.765298 0.7622377 ---------------------------------------------- David L Carlson Associate Professor of Anthropology Texas A&M University College Station, TX 77843-4352> -----Original Message----- > From: r-help-bounces at r-project.org [mailto:r-help-bounces at r- > project.org] On Behalf Of Yao He > Sent: Wednesday, December 26, 2012 6:54 PM > To: r-help at r-project.org > Subject: [R] how to apply two or more functions to each columns in a > time? > > Dear All: > > I want to calculate the mean and sd for each column in a data.frame. > > Taking data(iris) for example: > I tried sapply(iris[,-5],mean,na.rm=T) or sapply(iris[,-5],sd,na.rm=T) > to calculate the mean and sd .But sapply() transfer a function per > time. How to transfer two functions in a time to generate a data.frame > like this: > > Sepal.Length Sepal.Width Petal.Length Petal.Width > mean 5.84333 3.05733 3.758000 1.199333 > SD 0.82806 0.43586 1.765298 0.762237 > > > Thanks a lot > > Yao He > > -- > ------------------------- > Master candidate in 2rd year > Department of Animal genetics & breeding > Room 436,College of Animial Science&Technology, > China Agriculture University,Beijing,100193 > E-mail: yao.h.1988 at gmail.com > -------------------------- > > ______________________________________________ > 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.
Pete Brecknock
2012-Dec-27 01:56 UTC
[R] how to apply two or more functions to each columns in a time?
Yao He wrote> Dear All: > > I want to calculate the mean and sd for each column in a data.frame. > > Taking data(iris) for example: > I tried sapply(iris[,-5],mean,na.rm=T) or sapply(iris[,-5],sd,na.rm=T) > to calculate the mean and sd .But sapply() transfer a function per > time. How to transfer two functions in a time to generate a data.frame > like this: > > Sepal.Length Sepal.Width Petal.Length Petal.Width > mean 5.84333 3.05733 3.758000 1.199333 > SD 0.82806 0.43586 1.765298 0.762237 > > > Thanks a lot > > Yao He > > -- > ????????????????????????? > Master candidate in 2rd year > Department of Animal genetics & breeding > Room 436,College of Animial Science&Technology, > China Agriculture University,Beijing,100193 > E-mail:> yao.h.1988@> ?????????????????????????? > > ______________________________________________> R-help@> 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.Or maybe using apply .... # data d <- iris[,-5] # apply function a <-data.frame(apply(d, 2, function(x) c(mean=mean(x), sd=sd(x)))) # print(a) output Sepal.Length Sepal.Width Petal.Length Petal.Width mean 5.8433333 3.0573333 3.758000 1.1993333 sd 0.8280661 0.4358663 1.765298 0.7622377 HTH Pete -- View this message in context: http://r.789695.n4.nabble.com/how-to-apply-two-or-more-functions-to-each-columns-in-a-time-tp4654001p4654004.html Sent from the R help mailing list archive at Nabble.com.