matrix() can't handle NaN (PR#193)
Ben Bolker
ben@eno.princeton.edu
Tue, 11 May 1999 09:05:04 -0400 (EDT)
Perhaps this should be in a FAQ list ...
> data<-read.table("~/junk.dat",header=TRUE, na.strings="NaN")
> data
x y z
1 1 1 1
2 1 2 2
3 2 1 NA
4 2 2 4
> x<-unique(data$x)
> y<-unique(data$y)
> matrix(data$z,length(y),length(x))
[,1] [,2]
[1,] 1 NA
[2,] 2 4
"NaN" (Not a Number) as seen in debuggers, etc., is not the same as "NA"
as a "not available/applicable" value in R.
On Tue, 11 May 1999, Bill Simpson wrote:
>
>
> On Tue, 11 May 1999, Kurt Hornik wrote:
>
> > >>>>> wsi writes:
> >
> > > Full_Name: Bill Simpson
> > > Version: 0.64.1
> > > OS: linux
> > > Submission from: (NULL) (193.62.250.209)
> >
> >
> > > Here is the data file:
> > > x y z
> > > 1 1 1
> > > 1 2 2
> > > 2 1 NaN
> > > 2 2 4
> >
> > >> data<-read.table("~/junk.dat",header=TRUE)
> >
> > >> data
> > > x y z
> > > 1 1 1 1
> > > 2 1 2 2
> > > 3 2 1 NaN
> > > 4 2 2 4
> >
> I forgot these steps:
> x<-unique(data$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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Benjamin Bolker Dep't of Ecology and Evolutionary Biology,
ben@eno.princeton.edu Princeton University
tel: (609) 258-6886, fax: (609) 258-1334
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