A data processing means for user tunable and selectable (FIG. 2) of a database wherein the data contained therein have associated descriptive properties (FIG. 2) capable of being expressed in numeric form is described. Descriptive property values (FIG. 2) may be standardized numerically to eliminate property value overweighting. A quantized vector (FIG. 2) representative of the descriptive properties is created for each item in the database. This quantized vector becomes the fingerprint for each data item. The user submits a query item to be matched against the database for similarity. A fingerprint is calculated for the query item. The user may then assign weights to the individual descriptive properties based upon perceived importance (FIG. 2). A newly weighted fingerprint for the query item is then compared with the fingerprints for all the data in the database. A list of results is presented to the user (FIG. 2). The user may then change the previously assigned weights and then re-run the similarity search. This may be done as often as necessary to achieve the desired results. Similarity searching in a generic database is described. However, particulary the method is desirable in databases containing chemical compound structure data or biological response screening result data.