[R] How to compare X1 = X2 = ... = Xn?
ggrothendieck at myway.com
Mon Jul 19 20:48:47 CEST 2004
Gabor Grothendieck <ggrothendieck <at> myway.com> writes:
: F Duan <f.duan <at> yale.edu> writes:
: > I have a data frame with n columns: X1, X2, ., Xn. Now I want to create a
: > new column: if X1 = X2 = . = Xn, the value is 1; Otherwise, the value is 0.
: Here is one possibility if your data frame is all numeric:
: x$new <- (sd(t(x))==0)+0
: x is the data frame, new is the new column, sd(t(x)) is TRUE for
: rows with zero standard deviation (which occurs iff the entries
: are all zero) and FALSE otherwise and +0 converts that to 1 or 0.
"zero" should be replaced by "the same".
More information about the R-help