Bray-Curtis Dissimilarity Index Matrix

[Lee]

Is there any Matlab-code available that will create a Bray-Curtis
Dissimilarity Index Matrix? This index is widely used in multivariate
analysis of ecological communities.

Thanks in advance!

[reconf]

hi Lee,
Though i can not offer any help on this, i would like to as you
for some
more information( references/pointers) on this measure if dissimilarity.
thanks

[Lee]

Any ecological commnity analysis program worth its salt should have a
routine for calculating the Bray-Curtis dissimilarity index (e.g.,
PC-Ord, Primer, Patn, etc...)

--------------- Selected References: ---------------

Bray, J. R. and J. T. Curtis. 1957. An ordination of upland forest
communities of southern Wisconsin. Ecological Monographs 27:325-349.

Clarke, K. R. 1993. Non-parametric multivariate analyses of changes
in community structure. Australian Journal of Ecology 18: 117-143.

Faith, D. P., P. R. Minchin, and L. Belbin. 1987. Compositional
dissimilarity as a robust measure of ecological distance. Vegetatio
69:57-68.

Field, J. G., K. R. Clarke, and R. M. Warwick. 1982. A practical
strategy for analysing multispecies distribution patterns. Mar. Ecol.
Prog. Ser. 8:37-52.

Legendre, P. and L. Legendre. 1998. Numerical Ecology. 2nd English
edition. Elsevier, Amsterdam.

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On Wed, 24 Jan 2001 00:19:28 +0100, reconf <rec...@mailcity.com>
wrote:

[olivier]

function D = braycd(X1,X2)
% created by Olivier Zemb
% input : X1 and X2 as two row vectors containing the observations of the
% site 1 and site 2
% output : the bray curtis distance
% Note that this function can be used in combination with pdist.
% braycd= (Si+Sj -2 Cij)/(Si+Sj)

X=[X1; X2];
Cij=sum(min(X))

Si_plus_Sj=sum(X1)+sum(X2);

D=(Si_plus_Sj-2*Cij)/Si_plus_Sj;