Feature extraction and selection a Trying to extract discriminative features Trying to select robust feature components from the existing features Center of speech Technology, Tsinghua University Slide 6
Center of Speech Technology, Tsinghua University Slide 6 ❑ Trying to extract discriminative features ❑ Trying to select robust feature components from the existing features Feature Extraction and Selection
a Introduction human does not always use an identical feature to recognize objects s It is often that the feature components being used vary with the objects to be recognized This is feature selection after the feature extraction feature selection can be regarded as a special case of feature weighting Before going to the topic let's see a problem at first Center of speech Technology, Tsinghua University Slide 7
Center of Speech Technology, Tsinghua University Slide 7 ❑ Introduction ❖ Human does not always use an identical feature to recognize objects. ❖ It is often that the feature components being used vary with the objects to be recognized. ❖ This is feature selection after the feature extraction. ❖ Feature selection can be regarded as a special case of feature weighting. ❖ Before going to the topic, let’s see a problem at first
Room 1 Room 2 o0O0。O m八m B X 口 A Problem 冷 Conditions Two opaque and completely separated rooms are very close to each other Room 1 contains 3 switches and room 2 contains 3 lights Each switch is corresponding to one and only one light You can switch on/off any switch for any times But you can only enter each room for only once , Goal: finding which switch is corresponding to which light Center of speech Technology, Tsinghua University Slide 8
Center of Speech Technology, Tsinghua University Slide 8 ❑ A Problem ❖ Conditions: ➢ Two opaque and completely separated rooms are very close to each other. ➢ Room 1 contains 3 switches and Room 2 contains 3 lights. ➢ Each switch is corresponding to one and only one light. ➢ You can switch on/off any switch for any times. ➢ But you can only enter each room for only once. ❖ Goal: finding which switch is corresponding to which light. Room 1 Room 2 A B C X Y Z
Room 1 Room 2 “ O0 OOOO m八m B X Y a The answer(Step 1) Unseen 令 Actions Turn on switch a Wait fora couple of minutes Turn off Switch A Center of speech Technology, Tsinghua University Slide g
Center of Speech Technology, Tsinghua University Slide 9 Unseen A B C X Y Z Room 1 Room 2 ❑ The Answer (Step 1) ❖ Actions: ➢ Turn on Switch A. ➢ Wait for a couple of minutes ... ➢ Turn off Switch A
Room 1 Room 2 T/( B X Y 口 The answer(Step2) Unseen 令 Actions: Turn on Switch B Immediately go to Room 2 Center of speech Technology, Tsinghua University Slide 10
Center of Speech Technology, Tsinghua University Slide 10 Unseen A B C X Y Z Room 1 Room 2 ❑ The Answer (Step 2) ❖ Actions: ➢ Turn on Switch B. ➢ Immediately go to Room 2