install.packages('ffbase')
ffdf
to another ffdf
ffdf
from All Combinations of Factors...
does not contain factors, unique.ff
will add a levels attribute to the non-factors.ff
vectors.ff
vector x
ff
vectors.ff
vectorsdroplevels
is used to drop unused levels from a ff
factor or
, more commonly, from factors in a ffdf
ffdf
ff
vector Elementsis.na
indicates which elements are missing.
The generic function is.na<-
sets elements to NA
.droplevels
is used to drop unused levels from factors in a ffdf
ffdf
data.frameff
vectors.as.character
converts ff
vectors to characters.