Abstract: Methods and systems for managing an item assortment from among a collection of heterogeneous items are disclosed. One method includes receiving item data associated with the collection of heterogeneous items that defines values for a plurality of item attributes, and calculating a score for a degree of substitutability between items. A community detection algorithm is applied to edge weights that are based on the scores between items, to identify substitution groups among the items. Preferred attributes common to items within the substitution groups are found, and an item assortment is updated based on a determination of substitutability among items in at least one of the substitution groups.