Hi, I have a data-frame, r (column names below), that needs subsetting: date, time, strain, gene, deltact When I try to subset r by applying selection criteria on two columns I get an empty data frame. For example I would like to extract all rows that have time == 0h and strain == ROC. So, t <- subset(r, (r$time == "0h" && r$strain == "ROC"), select= c(time, strain, gene, deltact)) returns an empty data-frame. Is it not possible to subset based on two criteria? TIA Anjan -- ==================================anjan purkayastha, phd. research associate fas center for systems biology, harvard university 52 oxford street cambridge ma phone-703.740.6939 ================================== [[alternative HTML version deleted]]
'&&' is scalar 'and' you want to use the vector 'and' which is '&'. On 30/05/2010 16:14, ANJAN PURKAYASTHA wrote:> Hi, > I have a data-frame, r (column names below), that needs subsetting: > date, time, strain, gene, deltact > > When I try to subset r by applying selection criteria on two columns I get > an empty data frame. For example I would like to extract all rows that have > time == 0h and strain == ROC. > So, t<- subset(r, (r$time == "0h"&& r$strain == "ROC"), select= c(time, > strain, gene, deltact)) returns an empty data-frame. > Is it not possible to subset based on two criteria? > TIA > Anjan >-- Patrick Burns pburns at pburns.seanet.com http://www.burns-stat.com (home of 'Some hints for the R beginner' and 'The R Inferno')
try t <- subset(r, (r$time == "0h" & r$strain == "ROC"), select= c(time,strain, gene, deltact)) Do ?"&" to understand the difference between & and && . ANJAN PURKAYASTHA wrote:> > Hi, > I have a data-frame, r (column names below), that needs subsetting: > date, time, strain, gene, deltact > > When I try to subset r by applying selection criteria on two columns I get > an empty data frame. For example I would like to extract all rows that > have > time == 0h and strain == ROC. > So, t <- subset(r, (r$time == "0h" && r$strain == "ROC"), select= c(time, > strain, gene, deltact)) returns an empty data-frame. > Is it not possible to subset based on two criteria? > TIA > Anjan > > -- > ==================================> anjan purkayastha, phd. > research associate > fas center for systems biology, > harvard university > 52 oxford street > cambridge ma > phone-703.740.6939 > ==================================> > [[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. > >-- View this message in context: http://r.789695.n4.nabble.com/subsetting-tp2236334p2236388.html Sent from the R help mailing list archive at Nabble.com.
On May 30, 2010, at 11:14 AM, ANJAN PURKAYASTHA wrote:> Hi, > I have a data-frame, r (column names below), that needs subsetting: > date, time, strain, gene, deltact > > When I try to subset r by applying selection criteria on two columns > I get > an empty data frame. For example I would like to extract all rows > that have > time == 0h and strain == ROC. > So, t <- subset(r, (r$time == "0h" && r$strain == "ROC"),At least one error is the use of && instead of &. "&&" will only return a single value whereas "&" is the correct operator to use when working with vectors.> select= c(time, > strain, gene, deltact)) returns an empty data-frame. > Is it not possible to subset based on two criteria? > TIA > Anjan > > -- > ==================================> anjan purkayastha, phd. > research associate > fas center for systems biology, > harvard university > 52 oxford street > cambridge ma > phone-703.740.6939 > ==================================> > [[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.David Winsemius, MD West Hartford, CT