[R] Inconvenient behavior of as.data.frame() for lists without names

[Magnus Thor Torfason]

Hi all,

I ran into a small issue when converting a list of vectors to a data 
frame.  The Issue I'm having is described by the snippet below:

#########################################################
# Convert a list of vectors into a data.frame
strlen = 256
s.long.a = paste( letters[1+(0:strlen %% 26)], collapse="")
s.long.b = paste( letters[1+(strlen:0 %% 26)], collapse="")
v.long.a = rep(s.long.a, 2)
v.long.b = rep(s.long.b, 2)

# Convert when the list has no names for its elements
my.list = list(v.long.a, v.long.b)
my.df   = as.data.frame(my.list)

# Here we get an error
my.df

# This solves the problem
names(my.list) = c("a","b")
my.fixed.df = as.data.frame(my.list)
my.fixed.df
#########################################################

In short, the problem is that when there are no names attached to the 
elements of the list, it creates very long names - if the elements of 
the vectors themselves are long. And further, that names that are in 
some since disallowed (can't be printed, for one), are silently injected 
into a data.frame, leading to an error later on.

Better would be to error out in as.data.frame

Best would be if way of generating default names in this function would 
be intelligent enough to never create names longer than - say 30 
characters. Of course, explicit names should be honored.

Anyway, that's my thoughts on this issue. No patch attached, and I will 
work around this, but at least it is out there now.

Best,
Magnus Thor