[R] concise syntax for selecting multiple rows

[Gabor Grothendieck]

Here are four ways:

# state.name comes with R
DF <- data.frame(state = state.name, num = seq_along(state.name))

DF[DF$state %in% c("Iowa", "Utah"),]

subset(DF, state %in% c("Iowa", "Utah"))

subset(DF, grepl("Iowa|Utah", state))

library(sqldf) # see http://sqldf.googlecode.com
sqldf("select * from DF where state in ('Iowa', 'Utah')")


On Mon, Apr 26, 2010 at 11:12 AM, John Sorkin
<jsorkin at grecc.umaryland.edu> wrote:
> I would like to select rows if a row contains any one of several values. I can do the selection as follows:
>
> result[,"Subject"]=="JEFF" | result[,"Subject"]=="BG"
>
> But this is very unwieldily if one wishes to select many, many rows as one has to continuously repeat the source:
>
> result[,"Subject"]=="JEFF" | result[,"Subject"]=="BG" | result[,"Subject"]=="John"  |  result[,"Subject"]=="Mary"
>
> Is there an easier way? I tried the following but it did not work:
>
>
> result[,"Subject"]==c("JEFF" | "BG" | "John"  | "Mary")
>
> Thanks,
> John
>
>
>
> John David Sorkin M.D., Ph.D.
> Chief, Biostatistics and Informatics
> University of Maryland School of Medicine Division of Gerontology
> Baltimore VA Medical Center
> 10 North Greene Street
> GRECC (BT/18/GR)
> Baltimore, MD 21201-1524
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