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.
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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