[R] boot package
Rogério Rosa da Silva
rrsilva at ib.usp.br
Thu Mar 4 09:57:03 CET 2004
Dear all
As part of an ongoing study on the ecomorphology of ant communities, I have
obtained a matrix with 156 row (species) and 20 columns (several measurements
of body shape) for 4 localities.
For each community, I calculated a matrix of Euclidean distances between all
pairs of species. From this matrix, I extracted two measures of community
structure: i) I identified the distance from a individual to its nearest
neighbor (NND) in the morphological space and then calculated the averages of
the NND (MNND); ii) the mean of the Euclidean distances (MED). NND and MED
are of practical use in describing spatial relations between species. The
results of Euclidean distance studies in each of the four localities were
compared with each other for evidence repeating patterns.
To determine wheter ou not the morphological arrangement of species in
communities reflected internal organization, MNND and MED should be compared
with randomly generated communities.
It is possible to write a function in th boot package to evaluate the values
of average nearest-neighbor distance and of the mean of Euclidean distances
in randomly generated communities ? One set of 1000 random communities each
with 78, 90, 100 and 102 species must be generaded from the pool of species
(156 species). The only restrictions on species composition is that no
species could be placed in a community more than once, and only rows values
can be permuted.
Sorry, I don't know how to define the statistic term in the boot() function
from the boot library in R. I have studied the boot package, argument list of
functions and the functions definition. Can someone point me the correct
syntax?
I would very much appreciate any help
Best regards
Rogério
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