On Apr 20, 2013, at 2:03 PM, Bert Gunter wrote: > Dummy variables are not needed in R. > > Bert >
Bert is correct on this point, but if you what to know how the regression functions in R do this "behind the scenes" then you could always look at: ?model.matrix # where _some_ of the the automagical stuff happens > model.matrix( ~ crop, data=dat[,"crop", drop=FALSE]) (Intercept) cropSWHE 1 1 1 2 1 1 3 1 0 4 1 0 5 1 1 6 1 1 7 1 0 8 1 0 attr(,"assign") [1] 0 1 attr(,"contrasts") attr(,"contrasts")$crop [1] "contr.treatment" > Sent from my iPhone -- please excuse typos. > > On Apr 20, 2013, at 11:23 AM, shyam basnet <shyamabc2...@yahoo.com> wrote: > >> Hello R-users, >> >> The below is a snippet of my data: >> >> >> fid crop year value >> 5_1_1 SWHE 1995 171 >> 5_1_1 SWHE 1997 696 >> 5_1_1 BARL 1996 114 >> 5_1_1 BARL 1997 344 >> 5_2_2 SWHE 1995 120 >> 5_2_2 SWHE 1996 511 >> 5_2_2 BARL 1996 239 >> 5_2_2 BARL 1997 349 >> >> Here, I want to create dummy variables with the names of the content of a >> column 'crop' in a way that the new variable 'SWHE' would receive a value of >> 1 if the column 'crop' contains 'SWHE' and 0 otherwise. So, I would have two >> new variables SWHE and BARL as below: >> >> >> fid crop year value SWHE BARL >> 5_1_1 SWHE 1995 171 1 0 >> 5_1_1 SWHE 1997 696 1 0 >> 5_1_1 BARL 1996 114 0 1 >> 5_1_1 BARL 1997 344 0 1 >> 5_2_2 SWHE 1995 120 1 0 >> 5_2_2 SWHE 1996 511 1 0 >> 5_2_2 BARL 1996 239 0 1 >> 5_2_2 BARL 1997 349 0 1 >> >> >> Cheers, >> Shyam >> Nepal >> David Winsemius Alameda, CA, USA ______________________________________________ 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.
