[R] Replace missing values in lapply
Doran, Harold
HDoran at air.org
Wed Jan 24 17:15:50 CET 2007
I hadn't thought of that. I use the following at one point in my program
tmp <- with(data, tapply(variable, index, table))
Which returns a list. So, I just went with it for the rest of my
program. I'm changing code now to arrays, I think you're right and this
may be a better representation. I need to walk through this and see what
turns up.
Thanks for the recommendation.
> -----Original Message-----
> From: Gabor Grothendieck [mailto:ggrothendieck at gmail.com]
> Sent: Wednesday, January 24, 2007 11:06 AM
> To: Doran, Harold
> Cc: r-help at stat.math.ethz.ch
> Subject: Re: [R] Replace missing values in lapply
>
> I wonder if a list of matrices is the best representation?
> Do your matrices all have the same dimension as in:
>
> TP <- list(matrix(c(1:3, NA), 2), matrix(c(NA, 1:3), 2))
>
> # Then you could consider representing them as an array:
>
> TPa <- array(unlist(TP), c(2,2,2))
>
> # in which case its just
>
> TPa[is.na(TPa)] <- 0
> TPa
>
>
> On 1/24/07, Doran, Harold <HDoran at air.org> wrote:
> > I have some matrices stored as elements in a list that I am working
> > with. On example is provided below as TP[[18]]
> >
> > > TP[[18]]
> > level2
> > level1 1 2 3 4
> > 1 79 0 0 0
> > 2 0 0 0 0
> > 3 0 0 0 0
> > 4 0 0 0 0
> >
> > Now, using prop.table on this gives
> >
> > > prop.table(TP[[18]],1)
> > level2
> > level1 1 2 3 4
> > 1 1 0 0 0
> > 2
> > 3
> > 4
> >
> > It is important for the zero's to retain their position as
> this matrix
> > will subsequently be used in some matrix multiplication and hence,
> > must be of dimension 4 by 4 so that is it conformable for
> > multiplcation with another matrix.
> >
> > In looking at the structure of the object resulting from
> prop.table I
> > see NaNs, and so I can do this
> >
> > > rr <- TP[[18]]
> > > rr[is.na(rr)] <- 0
> > > rr
> > level2
> > level1 1 2 3 4
> > 1 79 0 0 0
> > 2 0 0 0 0
> > 3 0 0 0 0
> > 4 0 0 0 0
> >
> > This is exactly what I want for each matrix. But, I have multiple
> > matrices stored within the list that need to be changed and so I am
> > trying to resolve this via lapply, but something is awry
> (namely the
> > user), but I could use a little help.
> >
> > I was thinking the following function should work, but it
> doesn't. It
> > reduces each matrix within the list to a 0.
> >
> > PP <- lapply(TP, function(x) x[is.na(x)] <- 0)
> >
> > Am I missing something obvious?
> >
> > Harold
> >
> >
> > [[alternative HTML version deleted]]
> >
> > ______________________________________________
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> > PLEASE do read the posting guide
> > http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
> >
>
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