From thomas@biostat.washington.edu  Thu Feb 18 16:52:15 1999
From: thomas@biostat.washington.edu (Thomas Lumley)
Date: Thu, 18 Feb 1999 08:52:15 -0800 (PST)
Subject: model.frame mangles time series (PR#121)
In-Reply-To: <x2678zlkp6.fsf@blueberry.kubism.ku.dk>
Message-ID: <Pine.GSO.4.10.9902180851110.2878-100000@wompom.biostat.washington.edu>

On 18 Feb 1999, Peter Dalgaard BSA wrote:

> 
> (6) since [subset,] seems to work, perhaps do_subset is what should be
> called from inside do_modelframe?

No, subset doesn't work -- it loses contrasts

R>  contrasts(df$x)
  [,1] [,2]
1    1    0
2    0    1
3   -1   -1
R> contrasts(df[1:5,]$x)
  2 3
1 0 0
2 1 0
3 0 1
 
	-thomas


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model.frame mangles time series (PR#121)
Thomas Lumley