数据挖掘技术第九常用分类方法.ppt

数据挖掘技术 第九课 常用分类方法 主要内容 ? 基于规则的分类 ? 基于实例的分类 基于规则的分类（ Rule-Based Classifier ） ? 使用形如“ if…then…” 的规则集对记录进行分类。 ? 规则 : ( Condition ) ? y ? 其中 : ? Condition 是属性 - 值对的合取 ? y 是类标记 ? 分类规则的例子 : ? (Blood Type=Warm) ? (Lay Eggs=Yes) ? Birds ? (Taxable Income < 50K) ? (Refund=Yes) ? Evade=No 示例 R1: (Give Birth = no) ? (Can Fly = yes) ? Birds R2: (Give Birth = no) ? (Live in Water = yes) ? Fishes R3: (Give Birth = yes) ? (Blood Type = warm) ? Mammals R4: (Give Birth = no) ? (Can Fly = no) ? Reptiles R5: (Live in Water = sometimes) ? Amphibians Name Blood Type Give Birth Can Fly Live in Water Class human warm yes no no mammals python cold no no no reptiles salmon cold no no yes fishes whale warm yes no yes mammals frog cold no no sometimes amphibians komodo cold no no no reptiles bat warm yes yes no mammals pigeon warm no yes no birds cat warm yes no no mammals leopard shark cold yes no yes fishes turtle cold no no sometimes reptiles penguin warm no no sometimes birds porcupine warm yes no no mammals eel cold no no yes fishes salamander cold no no sometimes amphibians gila monster cold no no no reptiles platypus warm no no no mammals owl warm no yes no birds dolphin warm yes no yes mammals eagle warm no yes no birds 基于规则的分类的应用 ? 若实例 x 的属性值满足规则的条件，则称规则 r 覆 盖了实例 x R1: (Give Birth = no) ? (Can Fly = yes) ? Birds R2: (Give Birth = no) ? (Live in Water = yes) ? Fishes R3: (Give Birth = yes) ? (Blood Type = warm) ? Mammals R4: (Give Birth = no) ? (Can Fly = no) ? Reptiles R5: (Live in Water = sometimes) ? Amphibians The rule R1 covers a hawk => Bird The rule R3 covers the grizzly bear => Mammal Name Blood Type Give Birth Can Fly Live in Water Class hawk warm no yes no ? grizzly bear warm yes no no ? 分类规则的类别 ? 互斥规则 (Mutually exclusive rules) ? 若规则互相独立，则称分类器包含互斥规则 ? 每条记录最多被一条规则所覆盖 ? 无遗漏规则 (Exhaustive rules) ? 若分类器考虑了所有可能的属性值的组合，则 该分类器具有无遗漏的覆盖 ? 每条记录至少被一条规则所覆盖