Re: [Rd] (PR#14066) model.frame error with formula=~1 and na.action=na.fail

[Prof Brian Ripley]

Thank you for the report -- but a bit more investigation of the root 
cause would have been even more helpful: this is not 'model.frame 
error', nor even reported by R as such.


The issue was that complete.cases() did not know how to find the 
number of rows of a 0-column data frame (it knew nothing about data 
frames). That has been changed in R-patched and R-devel, together with 
a more informative error message in other cases where the number of 
rows is unspecified.


On Sun, 15 Nov 2009, sebastian.wastl.me...@campus.lmu.de wrote:


Full_Name: Sebastian Meyer
Version: 2.10.0
OS: x86_64-pc-linux-gnu
Submission from: (NULL) (77.135.124.96)


When using model.frame (model.frame.default) on an intercept-only model and with
na.action=na.fail SPECIFIED, i.e.

  data(iris)


That line is unnecessary: 'iris' is a visible object in package 
'datasets'.



  model.frame( ~ 1, data = iris, na.action = na.fail)

one gets the following error:

  Error in complete.cases(object) : negative length vectors are not allowed

There is no error if the na.action argument is left UNSPECIFIED (though the
default value also is na.fail!):

  model.frame( ~ 1, data = iris)

In either case, there should be no error. Specifing other na.action functions
(na.omit, na.pass, na.exclude) works.
If there is at least one (non-intercept) variable in the formula, e.g.

  model.frame( ~ 1 + Species, data = iris, na.action = na.fail)

there is obviously no issue.

Best regards,
   Sebastian Meyer

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--
Brian D. Ripley,  rip...@stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel:  +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UKFax:  +44 1865 272595

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Re: [Rd] (PR#14066) model.frame error with formula=~1 and na.action=na.fail

[Sebastian Meyer]

Thank you for your rapid bug fix and for your instructive comments on my
bug report.

 this is not 'model.frame error', nor even reported by R as such.

Of course you are right, but I thought that a bug report on model.frame
would probably reach more attention further providing a more motivating
frame for the bug than just writing that
complete.cases(as.data.frame(matrix(,150,0)))
would not work, and I was absolutely sure that you would be able to
track down the source of the problem.

 data(iris)

 That line is unnecessary: 'iris' is a visible object in package
 'datasets'.

Ok. I was not sure about this and just wanted to be on the save side to
offer a reproducible example working in a maximum variety of R sessions.

Best regards and thank you very much for your intense development of R,
   Sebastian Meyer

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