[R] select cases from a data.frame or matrix

[Peter Holzer]

Till Baumgaertel writes:
 > hi all,
 > 
 > is there a better solution to select rows from a data.frame than by iterating 
 > through the whole set and evaluating every case one by one? 
 > 
 > is there maybe something like:
 > d <- data.frame(...)
 > maleOver40 <- select.data.frame( d, "( sex=m or sex=M) and age > 40)")
 > 
 > of course, i could use direct database-requests, but this would require my data 
 > to be stored in a database...
 > 

maleOver40 <- d[(d$sex == "m" | d$sex == "M") & d$age > 40,]

 > thank you,
 > till
 > 
 > --
 > "I have seen things you people wouldn't believe.
 > Attack-ships  on fire off the shoulder of Orion.
 > I watched seabeams glitter in the dark near the 
 > Tannhauser gate.
 > All  those  moments  will  be lost in time like
 > tears in rain. Time to die."              (Roy)
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