On Oct 11, 2012, at 16:02 , Bert Gunter wrote:
... and further
identical(as.list(df2),as.list(df1))
[1] TRUE
in R 2.15.0
Not sure whether these sorts of degenerate cases are of much value,
though. But I'll leave that for the wizards.
Looks like this is easier to fix that to argue pro/con fixing it...
AFAICS, there's a gap in the logic in as.data.frame.matrix:
if (length(row.names) != nrows)
row.names - .set_row_names(nrows)
but length(NULL) is 0 so we can end up leaving row.names at NULL and eventually
nulling it in the result. An explicit check for is.null(row.names) should help.
-pd
-- Bert
On Wed, Oct 10, 2012 at 11:22 PM, Hervé Pagès hpa...@fhcrc.org wrote:
Hi,
Two ways to create what should normally be the same data frame:
df1 - data.frame(a=character(0), b=character(0)) df1
[1] a b
0 rows (or 0-length row.names)
df2 - as.data.frame(matrix(character(0), ncol=2, dimnames=list(NULL,
letters[1:2])))
df2
[1] a b
0 rows (or 0-length row.names)
unique() works as expected except that I get a warning on 'df2':
unique(df1)
[1] a b
0 rows (or 0-length row.names)
unique(df2)
[1] a b
0 rows (or 0-length row.names)
Warning message:
In is.na(rows) : is.na() applied to non-(list or vector) of type 'NULL'
Look like the two data frames are not identical:
identical(df1, df2)
[1] FALSE
all.equal(df1, df2)
[1] Attributes: Length mismatch: comparison on first 1 components
attributes(df1)
$names
[1] a b
$row.names
integer(0)
$class
[1] data.frame
attributes(df2)
$names
[1] a b
$class
[1] data.frame
Actually 'df2' is considered broken by validObject():
validObject(df1)
[1] TRUE
validObject(df2)
Error in validObject(df2) :
invalid class “data.frame” object: slots in class definition but not in
object: row.names
This is with R 2.15 and recent R devel.
Cheers,
H.
--
Hervé Pagès
Program in Computational Biology
Division of Public Health Sciences
Fred Hutchinson Cancer Research Center
1100 Fairview Ave. N, M1-B514
P.O. Box 19024
Seattle, WA 98109-1024
E-mail: hpa...@fhcrc.org
Phone: (206) 667-5791
Fax:(206) 667-1319
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--
Bert Gunter
Genentech Nonclinical Biostatistics
Internal Contact Info:
Phone: 467-7374
Website:
http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm
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--
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Email: pd@cbs.dk Priv: pda...@gmail.com
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