Hi Readers,
I have a question.
I have a large dataset and want to throw away columns that have the same
value in the column itself and I want to know which column this was.
For example
> x<-data.frame(id=c(1,2,3), snp1=c("A","G",
"G"),snp2=c("G","G","G"),snp3=c("G","G","A"))
> x
id snp1 snp2 snp3
1 1 A G G
2 2 G G G
3 3 G G A
Now I want to know that snp2 in monomorphic (the same value for the column)
and after I know which column it is I want to take these columns out.
Thanks,
Naomi
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Try this:> xid snp1 snp2 snp3 1 1 A G G 2 2 G G G 3 3 G G A> str(x)'data.frame': 3 obs. of 4 variables: $ id : num 1 2 3 $ snp1: Factor w/ 2 levels "A","G": 1 2 2 $ snp2: Factor w/ 1 level "G": 1 1 1 $ snp3: Factor w/ 2 levels "A","G": 2 2 1> # test for which columns are the same > apply(x, 2, function(.col) all(head(.col, -1) == tail(.col, -1)))id snp1 snp2 snp3 FALSE FALSE TRUE FALSE>On Thu, Mar 26, 2009 at 7:15 AM, Duijvesteijn, Naomi <Naomi.Duijvesteijn at ipg.nl> wrote:> > ? Hi Readers, > > > ? I have a question. > > > ? I have a large dataset and want to throw away columns that have the same > ? value in the column itself and I want to know which column this was. > > > ? For example > > ? > x<-data.frame(id=c(1,2,3), snp1=c("A","G", > ? "G"),snp2=c("G","G","G"),snp3=c("G","G","A")) > > ? > x > > ? ? id snp1 snp2 snp3 > > ? 1 ?1 ? ?A ? ?G ? ?G > > ? 2 ?2 ? ?G ? ?G ? ?G > > ? 3 ?3 ? ?G ? ?G ? ?A > > > ? Now I want to know that snp2 in monomorphic (the same value for the column) > ? and after I know which column it is I want to take these columns out. > > > ? Thanks, > > ? Naomi > > > > > > ? Disclaimer: ?De ?informatie opgenomen in dit bericht (en bijlagen) kan > ? vertrouwelijk zijn en is uitsluitend bestemd voor de geadresseerde(n). > ? Indien u dit bericht ten onrechte ontvangt, wordt u geacht de inhoud niet te > ? gebruiken, de afzender direct te informeren en het bericht te vernietigen. > ? Aan dit bericht kunnen geen rechten of plichten worden ontleend. > > ? ---------------------------------------------------------------------------- > ? ---------------------------- > > ? Disclaimer: The information contained in this message may be confidential > ? and is intended to be exclusively for the addressee. Should you receive this > ? message unintentionally, you are expected not to use the contents herein, to > ? notify the sender immediately and to destroy the message. No rights can be > ? derived from this message. > > ______________________________________________ > 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. > >-- Jim Holtman Cincinnati, OH +1 513 646 9390 What is the problem that you are trying to solve?
On Thu, Mar 26, 2009 at 12:15 PM, Duijvesteijn, Naomi <Naomi.Duijvesteijn at ipg.nl> wrote:> > ? Hi Readers, > > > ? I have a question. > > > ? I have a large dataset and want to throw away columns that have the same > ? value in the column itself and I want to know which column this was. > > > ? For example > > ? > x<-data.frame(id=c(1,2,3), snp1=c("A","G", > ? "G"),snp2=c("G","G","G"),snp3=c("G","G","A")) > > ? > x > > ? ? id snp1 snp2 snp3 > > ? 1 ?1 ? ?A ? ?G ? ?G > > ? 2 ?2 ? ?G ? ?G ? ?G > > ? 3 ?3 ? ?G ? ?G ? ?A > > > ? Now I want to know that snp2 in monomorphic (the same value for the column) > ? and after I know which column it is I want to take these columns out. > > > ? Thanks, > > ? Naomi >Another, perhaps slightly more intuitive solution than Jim's would be the following: x<-data.frame(id=c(1,2,3), snp1=c("A","G", "G"),snp2=c("G","G","G"),snp3=c("G","G","A")) is.monovalued<-function(df){ sapply(df,function(x){ length(unique(x))==1 }) } monovaluedCols<-is.monovalued(x) which(monovaluedCols) x[!monovaluedCols] /Gustaf -- Gustaf Rydevik, M.Sci. tel: +46(0)703 051 451 address:Essingetorget 40,112 66 Stockholm, SE skype:gustaf_rydevik
this works which.is.not.unique <- apply(x,2,function(x)ifelse(length(unique(x))==1,F,T)) x[,which.is.not.unique] patrizio 2009/3/26 Duijvesteijn, Naomi <Naomi.Duijvesteijn at ipg.nl>:> > ? Hi Readers, > > > ? I have a question. > > > ? I have a large dataset and want to throw away columns that have the same > ? value in the column itself and I want to know which column this was. > > > ? For example > > ? > x<-data.frame(id=c(1,2,3), snp1=c("A","G", > ? "G"),snp2=c("G","G","G"),snp3=c("G","G","A")) > > ? > x > > ? ? id snp1 snp2 snp3 > > ? 1 ?1 ? ?A ? ?G ? ?G > > ? 2 ?2 ? ?G ? ?G ? ?G > > ? 3 ?3 ? ?G ? ?G ? ?A > > > ? Now I want to know that snp2 in monomorphic (the same value for the column) > ? and after I know which column it is I want to take these columns out. > > > ? Thanks, > > ? Naomi > > > > > > ? Disclaimer: ?De ?informatie opgenomen in dit bericht (en bijlagen) kan > ? vertrouwelijk zijn en is uitsluitend bestemd voor de geadresseerde(n). > ? Indien u dit bericht ten onrechte ontvangt, wordt u geacht de inhoud niet te > ? gebruiken, de afzender direct te informeren en het bericht te vernietigen. > ? Aan dit bericht kunnen geen rechten of plichten worden ontleend. > > ? ---------------------------------------------------------------------------- > ? ---------------------------- > > ? Disclaimer: The information contained in this message may be confidential > ? and is intended to be exclusively for the addressee. Should you receive this > ? message unintentionally, you are expected not to use the contents herein, to > ? notify the sender immediately and to destroy the message. No rights can be > ? derived from this message. > > ______________________________________________ > 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. > >
Patrizio Frederic wrote:> this works > > which.is.not.unique <- apply(x,2,function(x)ifelse(length(unique(x))==1,F,T)) > x[,which.is.not.unique] >or you simplify that idea and say x[, apply(x, 2, function(x) length(unique(x)) > 1)] Uwe Ligges> patrizio > > 2009/3/26 Duijvesteijn, Naomi <Naomi.Duijvesteijn at ipg.nl>: >> Hi Readers, >> >> >> I have a question. >> >> >> I have a large dataset and want to throw away columns that have the same >> value in the column itself and I want to know which column this was. >> >> >> For example >> >> > x<-data.frame(id=c(1,2,3), snp1=c("A","G", >> "G"),snp2=c("G","G","G"),snp3=c("G","G","A")) >> >> > x >> >> id snp1 snp2 snp3 >> >> 1 1 A G G >> >> 2 2 G G G >> >> 3 3 G G A >> >> >> Now I want to know that snp2 in monomorphic (the same value for the column) >> and after I know which column it is I want to take these columns out. >> >> >> Thanks, >> >> Naomi >> >> >> >> >> >> Disclaimer: De informatie opgenomen in dit bericht (en bijlagen) kan >> vertrouwelijk zijn en is uitsluitend bestemd voor de geadresseerde(n). >> Indien u dit bericht ten onrechte ontvangt, wordt u geacht de inhoud niet te >> gebruiken, de afzender direct te informeren en het bericht te vernietigen. >> Aan dit bericht kunnen geen rechten of plichten worden ontleend. >> >> ---------------------------------------------------------------------------- >> ---------------------------- >> >> Disclaimer: The information contained in this message may be confidential >> and is intended to be exclusively for the addressee. Should you receive this >> message unintentionally, you are expected not to use the contents herein, to >> notify the sender immediately and to destroy the message. No rights can be >> derived from this message. >> >> ______________________________________________ >> 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.