dwinsemius at comcast.net
Sun May 30 18:43:35 CEST 2010
On May 30, 2010, at 11:14 AM, ANJAN PURKAYASTHA wrote:
> 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?
> anjan purkayastha, phd.
> research associate
> fas center for systems biology,
> harvard university
> 52 oxford street
> cambridge ma
> [[alternative HTML version deleted]]
> R-help at r-project.org mailing list
> 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
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