[R] request: How can we ignore a component of list having no element

[hadley wickham]

An alternative approach would be to store 0 x 0 matrices instead of
NULLs.  This way every object in your list is a consistent type.

Hadley

On Wed, Oct 15, 2008 at 5:23 AM, Muhammad Azam <mazam72 at yahoo.com> wrote:
> Dear friends
> There is a list of arrays comprising different no of rows and columns even sometimes NULL, such as [[2]] given below. How can we ignore [[2]] or others like this in the complete list. Any help in this regard is needed. Thanks
>
> [[1]]
>       [,1] [,2]
> [1,]    3    1
> [2,]    3    1
> [3,]    3    1
>
> [[2]]
> NULL
>
> [[3]]
>        [,1] [,2] [,3] [,4] [,5] [,6] [,7]
>  [1,]    3    1    0    0    0    0    0
>  [2,]    3    1    0    0    0    0    0
>  [3,]    3    1    0    0    0    0    0
>  [4,]    3    1    3    1    3    2    1
>  [5,]    3    1    3    1    3    2    1
>  [6,]    3    1    3    1    3    2    0
>
> [[4]]
>       [,1] [,2] [,3] [,4]
> [1,]    3    0    0    0
> [2,]    3    1    3    3
> [3,]    3    1    3    3
> [4,]    3    1    3    0
>
> OR
> x1=c(1,2,3); x2=c(1,2,3,4,6); x3=c(); x=list(x1,x2,x3)
>
> M.Azam
>
>
>
>        [[alternative HTML version deleted]]
>
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