rowIdx <- sample(nrow(a), size=nbrOfSamples) a[rowIdx,] and/or
colIdx <- sample(ncol(a), size=nbrOfSamples) a[,colIdx] /Henrik Bengtsson > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of > [EMAIL PROTECTED] > Sent: den 27 oktober 2003 16:26 > To: [EMAIL PROTECTED] > Subject: [R] how to select random rows ? > > > How can I select random subsets (rows!) from a data set ? > > If I generate simple data set > > > a <- data.frame(x=1:2, y = NaN, z = 2:1) > > a > x y z > 1 1 NaN 2 > 2 2 NaN 1 > > I can select random subsets (colums) very easily using sample > function: > > > sample(a, 2) > z y > 1 2 NaN > 2 1 NaN > > I expected that using transpose of a would do the same for > rows, but I am > getting > rather unexpected outcome > > > sample(t(a), 1) > <NA> > 1 > > R > > [[alternative HTML version deleted]] > > ______________________________________________ > [EMAIL PROTECTED] mailing list > https://www.stat.math.ethz.ch/mailma> n/listinfo/r-help > > ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
