October 2021
Intermediate to advanced
289 pages
8h 31m
Chinese
Content preview from 数据科学中的实用统计学(第2版)
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.
无监督学习
｜
263
7.5.3
分类数据和
Gower
距离
如果有分类数据，必须先通过排序（对于有序因子）或者将其编码为一组二元（虚拟）变
量，把它们转换为数值型数据。如果数据是由连续型变量和二元变量混合组成的，通常需
要对变量进行缩放，以使它们处于同一范围（参见
7.5.1
节）
。一种常用的缩放方法是使用
Gower
距离
。
Gower
距离的基本思想是，按照数据类型对每个变量使用不同的距离度量。
•
对数值变量和有序因子，使用两条记录之间的差的绝对值来计算距离（
曼哈顿距离
）。
•
对分类变量，如果两条记录的类别不同，它们的距离就是
1
；
如果类别相同，距离就是
0
。
Gower
距离的计算方法如下。
1.
对每条记录中所有变量
i
和变量
j
的两两组合，计算出它们之间的距离
d
i, j
。
2.
对
d
i,j
进行缩放，使得它的最小值是
0
，最大值是
1
。
3.
将缩放后的变量对之间的距离相加，使用均值或加权均值创建一个距离矩阵。
为了说明
Gower
距离，先使用
R
代码从贷款数据中取出几行：
> x <- loan_data[1:5, c('dti', 'payment_inc_ratio', 'home_', 'purpose_')]
> x
# A tibble: 5
×
4
dti payment_inc_ratio home purpose
<dbl> <dbl> <fctr> <fctr>
1 1.00 2.39320 RENT car
2 5.55 4.57170 OWN small_business
3 18.08 9.71600 ...
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.