[R] Could graph objects be stored in a "two-dimensional list"?

Jeff Newmiller jdnewmil at dcn.davis.CA.us
Thu May 23 18:06:27 CEST 2013


You could use lists of lists, and index them with vectors.

a <- list()
a[[1]] <- list()
a[[2]] <- list()
a[[c(1,1)]] <- g11
a[[c(1,2)]] <- g12
a[[c(2,1)]] <- g21
a[[c(2,2)]] <- g22
print(a[[c(2,1)]])

but this seems like an inefficient use of memory because your indexed data is stored more compactly than the graph object is. I would index the data and generate the graph object on the fly when I wanted to see it.
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jpm miao <miaojpm at gmail.com> wrote:

>Hi,
>
>I have a few graph objects created by some graphic package (say,
>ggplot2,
>which I use frequently). Because of the existent relation between the
>graphs, I'd like to index them in two dimensions as p[1,1], p[1,2],
>p[2,1],
>p[2,2] for convenience.
>
>To my knowledge, the only data type capable of storing graph objects
>(and
>any R object) is list, but unfortunately it is available in only one
>dimension. Could the graphs be stored in any two-dimensional data type?
>
>  One remedy that comes to my mind is to build a function f so that
>f(1,1)=1
>f(1,2)=2
>f(2,1)=3
>f(2,2)=4
>With functions f and f^{-1} (inverse function of f) , the
>two-dimensional
>indices could be mapped to and from a set of one-dimensional indices,
>and
>the functions are exactly the way R numbers elements in a matrix. Does
>R
>have this built-in function for a m by n matrix or more generally,
>m*n*p
>array? (I know this function is easy to write, but just want to make
>sure
>whether it exists already)
>
>   Thanks,
>
>Miao
>
>	[[alternative HTML version deleted]]
>
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