Hi
r-help-boun...@r-project.org napsal dne 19.08.2009 13:04:39:
> Strange, it doesn't work for me:
>
> Error in database[4, 4][[1]][1, ] : incorrect number of dimensions
> Execution halted
>
> R version 2.9.0 (2009-04-17) on Arch Linux, no additional packages
> installed.
database[4,4][[1]][,1]
does not work for me either but it is result of your complicated structure
of nested lists
This works
> database[4,4][[1]][[1]][,1]
[1] 0 1 1 1
See the structure
Matrix of lists
> database
[,1] [,2] [,3] [,4] [,5]
[1,] NULL NULL NULL NULL NULL
[2,] NULL NULL NULL NULL NULL
[3,] NULL NULL NULL NULL NULL
[4,] NULL NULL NULL List,1 NULL
[5,] NULL NULL NULL NULL NULL
List of lists
> database[4,4]
[[1]]
[[1]][[1]]
[,1] [,2] [,3] [,4]
[1,] 0 1 1 1
[2,] 1 0 1 1
[3,] 1 1 0 1
[4,] 1 1 1 0
List which contains your matrix
> database[4,4][[1]]
[[1]]
[,1] [,2] [,3] [,4]
[1,] 0 1 1 1
[2,] 1 0 1 1
[3,] 1 1 0 1
[4,] 1 1 1 0
Here is your matrix
> database[4,4][[1]][[1]]
[,1] [,2] [,3] [,4]
[1,] 0 1 1 1
[2,] 1 0 1 1
[3,] 1 1 0 1
[4,] 1 1 1 0
>
Regards
Petr
>
> David Winsemius schrieb:
> >
> > On Aug 19, 2009, at 6:02 AM, Michael Kogan wrote:
> >
> >> Unfortunately the matrix(list(),x,y) way seems to have some
> >> limitations. I want to continue working with the matrices which are
> >> saved in the database matrix. But for example the following doesn't
> >> work:
> >>
> >> tetrahedron=matrix(c(
> >> 0,1,1,1,
> >> 1,0,1,1,
> >> 1,1,0,1,
> >> 1,1,1,0
> >> ),nrow=4, byrow=TRUE) # an example matrix
> >>
> >> database=matrix(list(),5,5) # create database matrix
> >> database[[4,4]]=list(tetrahedron) # save example matrix in database
> >> matrix
> >>
> >> ## try to access the first row of the saved example matrix ##
> >> database[[4,4]][1] # prints the whole example matrix
> >
> > I was surprised that this worked. I would have expected that you would
> > have used:
> > database[4,4][[1]] since database is a matrix and generally one
> > accesses matrix elements
> > with "[<n>,<m>]" addressing, while the element is a list and would
> > need "[[<n>]]" addressing.
> >
> >> database[[4,4]][1][1,] # should have printed the first row of the
> >> example matrix, but gives:
> >
> > So I tried:
> >
> > database[4,4][[1]][1,]
> > # [1] 0 1 1 1 ....Success
> >
> >
> >>
> >> Error in database[[4, 4]][1][1,] : incorrect number of dimensions
> >> Execution halted
> >>
> >> The same happens with database[[4,4]][1,]... Is there any way to
> >> access the saved matrices like "normal" ones?
> >>
> >> Thanks,
> >> Michael
> >>
> >
> > David Winsemius, MD
> > Heritage Laboratories
> > West Hartford, CT
> >
>
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