Specifically note that, unlike C, R has true multidimensional arrays which are more than pointer jumps: the practical result of this is that you want to use a single subsetting ( x[i,j] ) and specify them both in one call -- x[i][j] instead gives you the "j"th element of the "i"th element which may or may not exist, but likely isn't what you are looking for.
On Wed, Aug 1, 2012 at 4:27 PM, Bert Gunter <gunter.ber...@gene.com> wrote: > Please read An Introduction to R, which ships with every copy of R, > where you will learn how to properly subscript data frames and lists, > among other things. There is a reason for such tutorials -- they > enable you to avoid elementary mistakes like this and wasting time and > effort with such posts as this. > > -- Bert > > On Wed, Aug 1, 2012 at 2:13 PM, Jie Tang <totang...@gmail.com> wrote: >> I defined a data.frame by a two-dimensional array. >>> aa = data.frame(rbind( 11:20, 1:10)) >>> aa >> X1 X2 X3 X4 X5 X6 X7 X8 X9 X10 >> 1 11 12 13 14 15 16 17 18 19 20 >> 2 1 2 3 4 5 6 7 8 9 10 >> >> Now I want to use the data in the second line of aa which from 1 to 10 to >> >> output.But I find that when I use the aa[[1]][1:10] and it seems be mistake. >> aa[[1]][1:10] >> [1] 11 1 NA NA NA NA NA NA NA NA You really just want this: aa[2, ] Second row -- not specifying the column returns all of them. And note that we are 1-based in our indexing here! Michael >> >> But when I just indice one element of the dataframe .e.g.aa[[1]][2] >> It will be ok. How could I subset the data.frame data by lines? >> >> Thank you ? >> >> -- >> TANG Jie >> Email: totang...@gmail.com >> Tel: 0086-2154896104 >> Shanghai Typhoon Institute,China >> >> [[alternative HTML version deleted]] >> >> ______________________________________________ >> 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. > > > > -- > > Bert Gunter > Genentech Nonclinical Biostatistics > > Internal Contact Info: > Phone: 467-7374 > Website: > http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm > > ______________________________________________ > 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.