[datatable-help] 1.7.9 submitted to CRAN

[Matthew Dowle]

NEW FEATURES

o  New function setnames(), referred to in 1.7.8 warning messages.
   It makes no copy of the whole data object, unlike names<- and
   colnames<-. It may be more convenient as well since it allows
   changing a column name, by name; e.g.,
        
     setnames(DT,"oldcolname","newcolname")  # by name; no match()
     setnames(DT,3,"newcolname")             # by position
     setnames(DT,2:3,c("A","B"))             # multiple
     setnames(DT,c("a","b"),c("A","B"))      # multiple by name
     setnames(DT,toupper(names(DT)))         # replace all
        
   setnames() maintains truelength of the over-allocated names vector.
This allows := to add columns fully by reference without growing the
names vector. As before with names<-, if a key column's name is changed,
the "sorted" attribute is updated with the new column name.
        
BUG FIXES

o  Incompatibility with reshape() of 3 column tables fixed
   (introduced by 1.7.8) :
       Error in setkey(ans, NULL) : x is not a data.table
   Thanks to Damian Betebenner for reporting and
   reproducible example. Tests added to catch in future.
        
o  setattr(DT,...) still returns DT, but now invisibly. It returns
   DT back again for compound syntax to work; e.g.,
       setattr(DT,...)[i,j,by]
   Again, thanks to Damian Betebenner for reporting.