For granularity, you can add a 2nd dimension to the category like
so:scarves:silkscarves:cottont-shirts:cottont-shirt:linenetc...Now, when
the user navigates your site, the category affinity array could look
like this:[scarves:cotton, t-shirts:cotton, t-shirts:linen,
t-shirts:silk, bedsheets:cotton]With this, you can see the visitor has
an affinity for t-shirts, and also affinity for cotton products.