[R] Replace missing values in lapply

[Doran, Harold]

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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