[Rd] Canberra distance
Christophe Genolini
cgenolin at u-paris10.fr
Sat Feb 6 16:39:31 CET 2010
Hi the list,
According to what I know, the Canberra distance between X et Y is : sum[
(|x_i - y_i|) / (|x_i|+|y_i|) ] (with | | denoting the function
'absolute value')
In the source code of the canberra distance in the file distance.c, we
find :
sum = fabs(x[i1] + x[i2]);
diff = fabs(x[i1] - x[i2]);
dev = diff/sum;
which correspond to the formula : sum[ (|x_i - y_i|) / (|x_i+y_i|) ]
(note that this does not define a distance... This is correct when x_i
and y_i are positive, but not when a value is negative.)
Is it on purpose or is it a bug?
Christophe
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