Thank all of you for your kindly help.
--- Jinsong Zhao <[EMAIL PROTECTED]> wrote: > Dear all, > > I hope to remove a whole column from a data frame or matrix (> 2000 > columns). All value in the column are same. The first thing is to > select those columns. > > For instance, I hope to remove the V3~6 column, for all the value in > those colume is zero. > > V3 V4 V5 V6 V7 V8 V9 V10 > 1 0 0 0 0 0.000 0.000 0.000 0.000 > 2 0 0 0 0 0.000 0.000 0.000 0.000 > 3 0 0 0 0 0.000 0.000 0.000 0.000 > 4 0 0 0 0 0.000 0.000 0.000 0.000 > 5 0 0 0 0 0.000 0.000 0.000 0.000 > 6 0 0 0 0 -0.001 -0.001 -0.001 -0.001 > 7 0 0 0 0 0.000 0.000 0.000 -0.001 > 8 0 0 0 0 0.000 0.000 0.000 -0.001 > 9 0 0 0 0 -0.009 -0.012 -0.015 -0.018 > > I mean how to select the first four columns. > > Thank you very much for your consideration on this matter. > > Best wishes, > > Jinsong > ===== (Mr.) Jinsong Zhao Ph.D. Candidate School of the Environment Nanjing University 22 Hankou Road, Nanjing 210093 P.R. China E-mail: [EMAIL PROTECTED] ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
