April 2020
Intermediate to advanced
816 pages
18h 32m
Chinese
Content preview from 精通機器學習
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.
149
第五章
支援向量機
支援向量機
（Support Vector Machine，SVM）
是一種既強大且用途廣泛的機器學習模型
，
能夠執行線性或非線性分類
、
回歸
，
甚至能夠偵測離群值
。
它是機器學習領域最熱門的模
型
，
每一位想要使用機器學習的人都應該把它放入工具箱
。SVM
特別適合用來對小型或
中型的資料組進行分類
。
本章將解釋
SVM
的核心概念
、
如何使用它們
，
以及它們如何運作
。
線性
SVM
分類
解釋
SVM
的基本概念最好的做法是使用一些圖片
。
圖
5-1
展示第
4
章結尾介紹的
iris
資
料組的一部分
，
它有兩個類別可以用一條直線明確地分開
（
它們是
可線性分隔的
）。
左圖
是三種線性分類器的決策邊界
。
產生虛線決策邊界的模型很糟糕
，
根本無法正確地分隔類
別
。
另外兩個模型都可以完美地處理這個訓練組
，
但是它們的決策邊界很接近實例
，
所以
這些模型在處理新實例時
，
可能沒有這麼好的表現
。
相較之下
，
右圖的實線代表
SVM
分
類器的決策邊界
，
這條線不但隔開兩個類別
，
它也盡量遠離最近的訓練實例
。
你可以將
SVM
分類器想成在類別之間放入最寬的街道
（
用平行的虛線來表示
）。
它稱為
大邊距分
類
（large margin classification）。
150
|
第五章：支援向量機
花瓣長度 花瓣長度
Iris versicolor
Iris setosa
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.