Schematic bit-string representation of a drug-human protein interaction profile. Each protein is represented by 3 bits to encode drug binding, drug activation, and drug inhibition of the protein, respectively. When a drug has been reported or predicted to bind, activate, or inhibit a protein, the bit representing the specific drug-protein interaction is turned on (assigned a value of 1). Otherwise, the bit is off (assigned a value of 0). M denotes the number of drugs with an approved indication (positive class), N denotes the total number of drugs, f
represents on-bit or off-bit of the i-th bit feature, A
denotes the number of on-bits of the i-th bit feature in the positive class, and B
denotes the number of on-bits of the i-th bit feature in all drugs.