1. A method, comprising: applying K-means type clustering to wafer maps comprising one or more spatial patterns to group one or more clusters comprising wafer maps having similar spatial patterns, each wafer map comprising data representing at least one property of a structure formed at each of a plurality of locations on a semiconductor wafer, the semiconductor wafer comprising a die at each location of the plurality of locations on the semiconductor wafer, and each die comprising at least one structure, the property of the structure being capable of being analyzed for a wafer yield determination; producing a dendrogram using a clustering process to display the one or more clusters; filtering out wafer maps based on factory tool and run date by applying a process based on an Apriori algorithm; and ranking the wafer maps that are not filtered out based on factory tool and run date by an ascending pareto-bound distance.