From Bill Simpson <wsi@gcal.ac.uk>  Tue May 11 14:48:57 1999
From: Bill Simpson <wsi@gcal.ac.uk> (Bill Simpson)
Date: Tue, 11 May 1999 13:48:57 +0000 (GMT)
Subject: matrix() can't handle NaN (PR#193)
In-Reply-To: <14136.9170.142518.789273@pc87.maho.magnaeu.com>
Message-ID: <Pine.LNX.3.96.990511133535.8568A-100000@cbe207.gcal.ac.uk>



On Tue, 11 May 1999, Kurt Hornik wrote:

> >>>>> wsi  writes:
> 
> > Full_Name: Bill Simpson
> > Version: 0.64.1
> > OS: linux
> > Submission from: (NULL) (193.62.250.209)
> 
> 
> > Here is the data file:
> > x y z
> > 1 1 1
> > 1 2 2
> > 2 1 NaN
> > 2 2 4
> 
> >> data<-read.table("~/junk.dat",header=TRUE)
> 
> >> data
> >   x y   z
> > 1 1 1   1
> > 2 1 2   2
> > 3 2 1 NaN
> > 4 2 2   4
> 
I forgot these steps:
x<-unique(data$x)
y<-unique(data$y)

> >> matrix(data$z,length(y),length(x)) 
> >      [,1] [,2]
> > [1,]    1    4
> > [2,]    2    3
> 
> > This is not the correct matrix.  It seems that NaNs screw up matrix().
> 
> Actually, data$z is a factor with one level NaN.
Geez, I why is data$z a factor?  That seems bizarre. It is supposed to be
the measured value (IV) at each combination of x and y. So what is the
right way to convert my original file?

I go through all this just to produce an image or contour or persp plot.

> R> data$z
> [1] 1   2   NaN 4  
> Levels:  1 2 4 NaN
Weird! Is this because matrix() interprets NaN as a character string
instead of as an NaN (which is a "number", isn't it?)?

Why then isn't everything converted to a factor?
> data$x
[1] 1 1 2 2
> data$y
[1] 1 2 1 2

Also, why does matrix() work as I expect when the NaN in the file is
changed to a 0:
> matrix(data$z,length(y),length(x))
     [,1] [,2]
[1,]    1    0
[2,]    2    4

It also works as I expect when the NaN is changed to an NA:
> matrix(data$z,length(y),length(x))
     [,1] [,2]
[1,]    1   NA
[2,]    2    4


> What you get is the codes of that, which I think is what you want.
NOPE! I want a matrix:
1	NaN
2	4

Bill

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matrix() can't handle NaN (PR#193)
Bill Simpson