From p.dalgaard@biostat.ku.dk  Thu Apr  6 19:47:44 2000
From: p.dalgaard@biostat.ku.dk (Peter Dalgaard BSA)
Date: 06 Apr 2000 20:47:44 +0200
Subject: [Rd] Strange behaviour of image (PR#510)
In-Reply-To: J.C.Rougier@durham.ac.uk's message of "Thu, 6 Apr 2000 20:15:05 +0200 (MET DST)"
References: <200004061815.UAA02888@pubhealth.ku.dk>
Message-ID: <x21z4jnk1b.fsf@blueberry.kubism.ku.dk>

J.C.Rougier@durham.ac.uk writes:

> The following commands
> 
> z <- matrix(seq(0, 1, len=1000))
> image(z, 1, z, zlim=c(0, 1), col=gray(1:10/10))
> 
> appear to violate the image functionality as described on the
> help page.  As I understand it, by specifying a zlim of c(0, 1)
> and a colour vector of length 10, the colours should correspond
> to the intervals (0, 0.1), (0.1, 0.2), ..., (0.9, 1.0), this
> being 10 equally-spaced intervals on (0, 1).  It is clear from
> the image that this has not occurred.  In fact the intervals are
> apparently (0, 1/18), (1/18, 3/18), ..., (15/18, 17/18), (17/18,
> 1).  Have I misunderstood something?

I don't see that anything else is being promised...

If someone actually thought about this, then the choice might be
related to the behavior at peaks and troughs. (since a circle with
radius r looks wide compared to the region between two circles with
diameter n*r and (n+1)*r)

-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk)             FAX: (+45) 35327907
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[Rd] Strange behaviour of image (PR#510)
Peter Dalgaard BSA