Hi r-help-boun...@r-project.org napsal dne 19.04.2011 09:46:47:
> Dear R Users, > > Lets assume I have this data frame: > > x y z > 1 1.00 5 0.5 > 2 1.02 5 0.7 > 3 1.04 7 0.1 > 4 1.06 9 0.4 > > x and y columns are sorted and the values not necessarily integers. z > values are not sorted. Now I would like to create a matrix out of this > with x as first column values and y as first row values. Matrix element > a_11 shall be left NA. The a_ij should have the z value for the > corresponding x and y pair. The result shall be some sort of a grid and > then e.g. look like: > > [,1] [,2] [,3] [,4] [,5] > [1,] NA 5 6 7 9 (y) > [2,] 1.00 0.5 NA NA NA > [3,] 1.02 0.7 NA NA NA > [4,] 1.04 NA NA 0.1 NA > [5,] 1.06 NA NA NA 0.4 > (x) > > This example is just for illustration. The resulting matrix should have > more numeric values than NA's. I am not sure if this is the solution you want tab<-xtabs(z~x+y, data=df) tab[tab==0]<-NA Regards Petr > > I hope I made myself clear. Any hints on how to achieve this? Is there > already a function that does it? All searches I did pointed me to data > type frame to matrix conversion... > > Kind Regards, > Michael Bach > > ______________________________________________ > R-help@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. ______________________________________________ R-help@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.
